321. She (to want) to know how many children I (to have). 322. Who (to give) you that ring? I never (to see) it before. 323. If they (not to hurry) the train (to start off) by the time they come to the station. 324. He (to stand) there, his hands in his pockets, as if he (not to see) anything around him. 325. We (to discuss) your mistakes at the next lesson if we (not to manage) to do it now. 326. He used to be a heavy smoker, and though he (to know) that it (to be) very dangerous he never gave it up. 327. He (to get married) a year ago and he (to change) much since then. 328. He (not to see) his brother since he (to do) his military service. 329. I went back to the place where I (to buy) my scarf, but it (to be closed). 330. The sportsman (to be sure) that he (to take part) in the next competition. 331. Andrew (to come) to see us this evening, so I (to decide) to come home earlier than usual. 332. He (to become) quite different since he (to get married). 333. When they (to arrive) at the theatre, the first act (to start). 334. He (to do) the translation while you (to be busy) in the kitchen. 335. They (to want) to leave after Jim (to pass) all his exams. 336. He (to wait) for Ann, when we (to see) him.

She wanted to know how many children I had.
wanted — Past Simple; had — Past Simple по правилу согласования времён в косвенном вопросе.

Who gave you that ring? I have never seen it before.
gave — Past Simple, так как спрашивают о совершённом действии; have never seen — Present Perfect, поскольку речь идёт об опыте до настоящего момента.

If they do not hurry, the train will have started off by the time they come to the station.
В условном предложении первого типа после if используется Present Simple — do not hurry. Will have started off — Future Perfect: поезд уже отправится к моменту их прибытия. После by the time в значении будущего используется Present Simple — come.

He stood there, his hands in his pockets, as if he did not see anything around him.
stood и did not see — Past Simple. Действия относятся к одной ситуации в прошлом: он стоял так, словно ничего вокруг не замечал.

We will discuss your mistakes at the next lesson if we do not manage to do it now.
Это условное предложение первого типа: will discuss — Future Simple в главной части, do not manage — Present Simple после if.

He used to be a heavy smoker, and though he knew that it was very dangerous, he never gave it up.
knew, was, gave up — Past Simple, потому что всё предложение описывает факты и привычки прошлого.

He got married a year ago, and he has changed much since then.
got married — Past Simple, так как указано точное время: a year ago. Has changed — Present Perfect, поскольку изменение произошло за период с того момента до настоящего времени.

He has not seen his brother since he did his military service.
has not seen — Present Perfect: он не видел брата с определённого момента до настоящего времени. После since для обозначения начального момента используется Past Simple — did.

I went back to the place where I had bought my scarf, but it was closed.
went и was — Past Simple. Had bought — Past Perfect, потому что покупка шарфа произошла раньше, чем возвращение в магазин.

The sportsman was sure that he would take part in the next competition.
was — Past Simple. Would take part — Future in the Past: участие в соревновании являлось будущим действием с точки зрения прошлого.

Andrew is coming to see us this evening, so I have decided to come home earlier than usual.
is coming — Present Continuous для запланированного действия в будущем. Have decided — Present Perfect: решение уже принято и важно в настоящий момент.

He has become quite different since he got married.
has become — Present Perfect, поскольку изменение произошло к настоящему моменту. После since употребляется Past Simple — got married.

When they arrived at the theatre, the first act had started.
arrived — Past Simple. Had started — Past Perfect, потому что первый акт начался до того, как они приехали в театр.

He was doing the translation while you were busy in the kitchen.
was doing — Past Continuous, так как перевод выполнялся в течение некоторого времени в прошлом. Were — Past Simple глагола to be. Оба состояния происходили одновременно.

They wanted to leave after Jim had passed all his exams.
wanted — Past Simple. Had passed — Past Perfect, потому что Джим должен был сначала сдать все экзамены, а уже после этого они собирались уехать.

He was waiting for Ann when we saw him.
was waiting — Past Continuous для продолжительного действия в прошлом. Saw — Past Simple для короткого действия, которое произошло во время ожидания.