Công thức thì HTHT

(+) S + has/have + V3/ed 

(-) S + has/have + not + V3/ed 

(?) Has/Have + S+ V3/ed?

DHNB: before, since + mốc thời gian, for + khoảng thời gian, yet, already, just,....

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EX1:

a) since 

b) for 

c) since 

d) since 

e) for 

f) since 

g) for 

h) since 

i) for 

j) since 

k) for 

l) for 

m) for 

n) since 

o) for 

p) since 

EX2:

a. has lived / for 

b. has known / since 

c) has been / for 

d) has lived / since 

e) haven't played / for 

f) haven't seen / since 

g) have studied / for 

h) hasn't spoken / for 

i) have been / for 

j) has looked / for