`1.` 

`(?)` Were there many homeless people here ten years ago?

`(+)` There were many homeless people here ten years ago.

Giải thích: thì Quá khứ đơn với động từ tobe:

$\text{(+) S + was/were + ...}$

$\text{(-) S + was/were not + ...}$

$\text{(?) Was/Were + S + ...?}$

`2.` 

`(-)` Tom's grandfather didn't use to be a soldier?

`(+)` Tom's grandfather used to be a soldier.

Giải thích: thì Quá khứ đơn với động từ thường.

$\text{(+) S + Ved/V2 + ...}$

$\text{(-) S + didn't + V-bare + ...}$

$\text{(?) Did + S + V-bare + ...?}$

$chucbanhoctot$

$\textit{~KaitoKid!}$

(-)there were not many homeless people here ten years ago

(?) Were there many homeless people here ten years ago ?

` => `  Were + S +O ?

(+) there were many homeless people here ten years ago

` => ` S + were + O

___________________________________________________________________

(?) Did Tom's grandfather use to be a soldier?

(-) Tom's grandfather didn't use to be a soldier

` => `  S + did not + V (nguyên mẫu)

(+) Tom's grandfather used to be a soldier

=> thì quá khứ nên chia động từ :S + V2/ed + O

` \color{lightblue}{\text{#Sunny Mery} `