浮阀塔的浮阀标准重量有轻阀和重阀，其重量为（）
A、25g和33g
B、20g和33g
C、25g和30g
参考答案：A
The boat _____ like a duck. [ ]
A. isn't look
B. don't look
C. doesn't look
D. doesn't looks
水中悬浮物质粒径大小一般为（）
A.10-4mm以上
B.10-4--10-5mm
C.10-5--10-6mm
D.10-6--10-7mm
