根据短文内容判断正(T)误(F)。

      It's Sunday morning. The students of Class 3 are giving their classroom a good cleaning. Miss Huang,

their teacher, is working with them. The children are busy. Some are carrying water; some are cleaning the

windows; others are sweeping the floor. Zhang Hua is putting up a map on the wall. It is a map of China.

Wang Fei and Wei Qing are mending some broken chairs. The children are listening to the radio while they

are working. The classroom looks nice and bright after the cleaning. The children are very happy. They go

home for lunch at noon.

( ) 1. The children are playing in their classroom on Sunday morning.

( ) 2. Miss Huang, their mother, is working with them.

( ) 3. There is a map of China on the wall.

( ) 4. Two of them are repairing the broken chairs.

( ) 5. They are singing while they are working.

搪瓷厂制造一种铁盒，用直径为0.4米的圆形铁皮可以做成一个。如果每天生产450个这样的铁盒，共需铁皮多少平方米？