Bobby 
throws
 a banana skin
 on the ground. He likes eating
 bananas. Tina is very angry. She says, "Bobby, you can't
 do that. Pick
 it up
, please. It makes
 the street messy
 and dirty
."答案:throws, skin, eating, can't, Pick, up, makes, messy, dirty
1. Rubbish 
2. There is rubbish on the ground. Please
3. To
4. My brother always
made
 the river dirty
 many years ago.2. There is rubbish on the ground. Please
pick
 it up
 and then put
 it in
 the bin.3. To
keep
 our classroom clean
, we sweep the floor every day.4. My brother always
helps
 me with
 my English.答案:1. made, dirty 2. pick, up, put, in 3. keep, clean 4. helps, with
1. Sam slips on those 
2. What can we do
3. We should
4. Some clothes
5. There
6. He helps
7. Bobby likes
banana skins
 and falls
.2. What can we do
to help
 him?3. We should
put
 rubbish in the bins to keep
 the park clean.4. Some clothes
make
 the bed messy.5. There
is
 rubbish in the street.6. He helps
(to) clean
 the desks.7. Bobby likes
living
 in the city.答案:1. banana skins, falls 2. to help 3. put, to keep 4. make 5. is 6. (to) clean 7. living
1. Black smoke from f
2. Mike went to the Palace M
3. Your i
4. The dirty water makes the fish d
5. To k
6. We can take the m
factories
 makes the air ddirty
.2. Mike went to the Palace M
Museum
 for the holiday.3. Your i
ideas
 are good.4. The dirty water makes the fish d
dead
.5. To k
keep
 the classroom clean, we can ssweep
 the floor. We can't throw rrubbish
 on the ffloor
.6. We can take the m
metro
 to school.答案:1. factories, dirty 2. Museum 3. ideas 4. dead 5. keep, sweep, rubbish, floor 6. metro