Last week, a schoolboy (see)..something in the sky as he was walking home.

Chia theo thì gì vậy ạ?

Answer: Last week, a schoolboy saw something in the sky as he was walking home. 

Trong câu trên, hành động 1 xảy ra bất chợt khi hành động hai đang xảy ra nên chia V ở dạng quá khứ đơn.

=> Chia theo thì quá khứ tiếp diễn 

+) I/He/She/It was + V-ing

    We/You/They were + V-ing

-) I/He/She/It was not + V-ing

    We/You/They were not + V-ing

?) Was I/He/She/It + V-ing?

    Were We/You/They + V-ing?

@Phamnqan