theirs  
#13381
A
thread
B
smooth
C
thirsty
D
health
推荐题目
Modern education is _____ sitting at a desk and looking at the blackboard. 
#12376
A
no more than
B
not less than
C
more than
D
less than
Every minute is made full _____ of _____ our lessons well.
#12670
A
to use; study
B
use; studying
C
use; to study
D
used; studying