----This returned Chinese scholar has become one of the top experts in this field.----Yes,I know him very well.He____in Africa with animals for eight years.
#104192
A
has worke
B
had worked
C
worked
D
has been working
推荐题目
Hurry! The train _______. You know it _____at 8:30am. .
#101032
A
leaves; leaves
B
is leaving; leaves
C
leaves; leaving
D
is leaving; is leaving
The country life he was used to ____ greatly in the past decade. 
#101394
A
change
B
has changed
C
changing
D
have changed
Although all of the apples _____, none of them _____ good.
#102362
A
have tasted; are tasted
B
have been tasted; are tasted
C
have tasted; taste
D
have been tasted; taste