The split between humans and living apes is thought by some scholars ____ 15 to 20 million years ago.
#96013
A
to occur
B
occurring
C
to have occurred
D
having occurred
推荐题目
He gave a ________smile. 
#97353
A
satisfying
B
satisfied
C
satisfaction
D
satisfactory
— What’s the matter with you?—______the heavy suitcase, my waist was hurt unexpectedly.
#96996
A
Carrying
B
Carried
C
While carrying
D
While I was carrying