when - is used to show that something happened at the same time (short action), while - is used to show that something happened at the same time (long action), during - refers to a period of time, after; as soon as - is used to show actions one after another , by - is used with noun to show the action which is (was) happening before a particular moment, until (till) - refers to a point of time,

linkers and time expressions

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