Until recently historians assumed that calendars ________ with the advent of agriculture.
#76571
A
came to existence
B
came to existing
C
came to exist
D
were existential
推荐题目
All my pockets have been ________ but I can’t find my keys.
#64252
A
got through
B
given out
C
gone through
D
gone down
 The level of the river ___ 20 centimeters over the security line and ____must be taken to control the flood. 
#74864
A
is measured; measures
B
measures; measurement
C
measures; measures
D
is measured; measurement