词型转换：
1. We must pay attention to wild animals because many of them are in danger of （die）out .
2. It （be）four years since we （learn）English at school .
3. I’m sorry （trouble）you .
4. you （receive）a letter from your father recently ?
5. There’s a student （call）Owen in our class .
6. Tell him what （eat）this evening .
7. They decided that they （go）to the park if it （not rain）the next day .
8. Tom said he （never hear）of that .
9. By the end of last week we （visit）about ten factories in this city .
10. What foreign language （teach）in your school ?
1. dying 2. is（has been）, learned
3. to trouble 4. Have received
5. called 6. to eat 7. would go , didn’t rain
8. had never heard
9. had visited 10. is taught