太阳系是由以下哪些物质构成的？（）
A.太阳
B.行星
C.彗星
D.星际物质
参考答案：A, B, C, D
_____ you read the sentences , _____ mistakes you’ll make.
A．More carefully, fewer
B． The more carefully, the less
C．The more careful , the fewer
D．The more carefully, the fewer
液压舵机液压油温度一般不允许超过（）。
A.50°C
B.60°C
C.70°C
D.80°C
