设a=350,b=440,c=530,则a、b、c的大小关系是 [ ]
A. a>b>c
B. b>a>c
C. a>c>b
D. c>a>b
答案:B
We________on this project for four hours.Let's have a rest.
A.are working
B.have been working
C.worked
D.had worked
冷却水出水温度不应超过()℃。
A.30
B.40
C.50