$\text{*}$ Đáp án $\text{+}$ Giải thích các bước:

$\text{11}$. Mrs. Green always goes to work by bus.

$\text{⇒}$ Always $\text{→}$ Dấu hiệu hiện tại đơn

$\text{12}$. We are from French. We have been there for 20 years.

$\text{⇒}$ For $\text{+}$ time $\text{→}$ Dấu hiệu hiện tại hoàn thành

$\text{13}$. I will move to another town next week.

$\text{⇒}$ Next $\text{→}$ Dấu hiệu tương lai đơn

$\text{14}$. I have seen that film several times because I like it.

$\text{⇒}$ Several times $\text{→}$ Dấu hiệu hiện tại hoàn thành

$\text{15}$. She always goes to bed before her mother does.

$\text{⇒}$ Always $\text{→}$ Dấu hiệu hiện tại đơn

$\text{16}$. Mary has lost her hat for 2 days.

$\text{⇒}$ For $\text{+}$ time $\text{→}$ Dấu hiệu hiện tại hoàn thành

$\text{17}$. Will you take a trip to London next week?

$\text{⇒}$ Next $\text{→}$ Dấu hiệu tương lai đơn

$\text{18}$. She rarely takes a bath before dinner.

$\text{⇒}$ Rarely $\text{→}$ Dấu hiệu hiện tại đơn

$\text{19}$. He hasn't finished doing it yet.

$\text{⇒}$ Yet $\text{→}$ Dấu hiệu hiện tại hoàn thành

$\text{20}$. He hasn't seen him since Christmas.

$\text{⇒}$ Since $\text{→}$ Dấu hiệu hiện tại hoàn thành

Chúc bạn học tốt!

@MyChan @vietha281

`11 ` : goes

HTĐ : S + Vs/es

DHNB : always

` 12 ` : are - have been

We /you / they + are 

HTHT + for : S + have /has +VPII + for + 1 khoảng TG

DHNB : for 20 years

` 13 ` : will move

TLĐ : S + will+ V nguyên mẫu

DHNB : next week

` 14 ` : have seen

HTHT : S + have / has + VPII

DHNB : several times

` 15 `: goes

HTĐ : S + Vs/es

DHNB : always

` 16 ` ; has lost

HTHT + for : S + have /has +VPII + for + 1 khoảng TG

DHNB : for 2 days

` 17 ` : Will - take

TLĐ :Will + S + V nguyên mẫu

` 18 ` : takes

HTĐ : S + Vs/es

DHNB : rarely

` 19 ` : hasn't finished

HTHT + yet : S + haven't / hasn't + VPII + yet

` 20 ` : hasn't seen 

HTHt + since : S +have / has + VPII + since +1 mốc TG