以“Good habits on the road”为题，说一说，写一写。
On the road, we must __________________________.
There's the red man. We must __________________________.
There isn't a zebra crossing. We must __________________________.

1. 读下列单词，再写出其否定形式。
can→(　　　　　　　　) must→(　　　　　　　　)
could→(　　　　　　　　) are→(　　　　　　　　)

2. 将下面句子正确、规范地抄写在四线格里。
How can you cross the road safely?
You must look at the traffic lights.
______________________________

2. 根据句意，选择合适的词填空。
(1) We __________ (should/shouldn't) go to bed late at night.
(2) To keep safe, we __________ (mustn't/must) run or play on the road.
(3) To keep healthy, we __________ (must/mustn't) eat some fruit and vegetables.
(4) —Can I sing __________ (loudly/loud)?
—No, you __________ (can/can't). My little brother is sleeping now.
(5) —What __________ (should/shouldn't) I do in the library?
—You shouldn't read __________ (quietly/loudly).