阅读对话并判断正(T)误(F)。

A: How do you spend your weekends, Mike?

B: I often go swimming. How about you, David?

A: I like swimming, too. Do you often do housework at home?

B: Yes, I do. I often clean my rooms and wash my clothes.

A: What are you doing now?

B: I'm watching cartoons now. My mother usually watches cartoons with me, too.

( )1. Mike often goes swimming.

(     )2. Mike often cleans rooms at the weekends.

(     )3. David is watching cartoons with his father.

(     )4. David's hobby is swimming.

( )5. Mike usually washes clothes at night.

诊断用X射线机房的主防护铅当量厚度应是（）.

A.0.5mm

B.1.0mm

C.1.5mm

D.2.0mm

E.2.5mm