--When _____ the abacus _____? -- In the sixth century by the Chinese people.
#44867
A
is, invented
B
did, invent
C
was, invented
D
does, invent
推荐题目
An official _____ by some reporters on food problems in Shanghai yesterday.
#44962
A
is interviewing
B
is interviewed
C
was interviewing
D
was interviewed
You have to be 18 years before you _________ to drive a car.
#44890
A
are allowed
B
are
C
allowed
D
allow
While he the bus, he a book.
#44868
A
was waiting for, read
B
waited for, was reading
C
was waiting for, was reading
D
waited for, read
China has offered much help to Japan since it ______ by the earthquake and tsunami（海啸）.
#44983
A
hits
B
is hit
C
was hit
D
will be hit
More and more people have realized that we won’t have cleaner water to drink unless something _______soon.
#44577
A
is done
B
was done
C
will be done
D
to be done