采用定向装配法来提高主轴的旋转精度，如前后轴承（）相同，主轴的径向跳动量反而增大。
A.尺寸
B.精度
C.重量
D.形式
参考答案：B
选词填空。
What colour, What time,
What, Where, Who
1. — is the canteen?
— It's on the first floor.
2. — Is your T-shirt?
— It's yellow.
3. — is that boy?
— He is my brother.
4. — is it?
— It's 7 :00.
5. — is that?
— It's a dog.
下列药剂不能混合使用的是（）。
A.二氯杀螨醇与堆肥
B.波尔多液与石硫合剂
C.乐果与敌敌畏
D.托布津与代森锌
