When it comes to the words when and while in English, we need to know that they are used to represent time, and there is a certain pattern in their use!
Let's start with when:
When it can be a specific point in time or a period of time. It's so powerful to describe the past, present, or future time!
Then when when describing the past time, the main clause usually also uses the past tense, while the subordinate clause can use the simple past tense or the past continuous tense. For example: "I was reading a book and he came." ”
And when when describing the time in the future, the main clause will use the future tense and the clause will use the simple present tense. For example: "I'll visit you when I'm free." ”
Let's talk about while:
While is mainly used to represent a period of time, that is, "in ......Period", which emphasizes a continuous action or state.
When while describes the past time, the clause is usually used in the past tense, emphasizing the continuity of the background action. The main clause can be in the past tense or in the past continuous tense. For example: "I'm reading a book and he's watching TV at the same time." ”
To sum up, when using when and while, we must pay attention to the continuity and termination of the verb in the temporal adverbial clause they guide, as well as the tense relationship between the main clause and the clause. Generally speaking, the verbs in the subordinate clauses guided by when and while should be continuous, so that the expression is more authentic and accurate!