With which tense do we use 'as'? [closed]

Here, you are using "as" to mean "while something else is happening" (Advanced Learner's Oxford Dictionary).

You use the past simple because you are talking about an action entirely contained in the past and you choose to consider the period of time when it happens as a specific time; you could have chosen the past progressive, though, thereby formulating that the action is considered as occurring over a time span.

• As the plane was taking off, I held my mum's hand tightly.

You can use "as" with many tenses. In particular it can be used with the state present and continuous tenses.

Examples

• As the Earth revolves about the sun, so does the Moon revolve about the Earth. (state present)

• You have to look for traces along the path as you are getting close to the hill, that's where the animal is found most often. (present continuous)

• As she was preparing breakfast, she remembered there was no bread left. (past continuous)

The simple past can also be used, but as well the present perfect.

Examples

• She felt a sharp pain in her shoulder as she removed her shirt. (simple past)

• As she has said all along, she wasn't in the school on the day of the robbery, she was sick, she can't be guilty. (present perfect)

You can also use the future and the future continuous.

Examples

• As you will close the door, it will be latched automatically. (future)

• They'll make that experiment in the morning, as the sun will be rising. (future continuous)