Medical researchers are painfully aware that there are many problems__________(他们至今还没有答案)
举一反三
- There are many problems wait for people to solve and theses problems are tough. A: Many tough problems are waiting for people to solve. B: Many problems are waiting for people to solve and these problems are tough. C: Many problems which are tough are waiting for people to solve. D: Many problems are waiting for people to solve even though they are tough.
- We are aware of the _________ problems and have taken every precaution.
- What is the cause of many problems in familiesThe cause of many problems in families is（）.
- On a daily basis, how many passengers with serious in-flight medical problems call for pilots to turn the flight around A: 2. B: 4. C: 5. D: 14.
- Not until this week were they aware of the problems with the air-conditioning units in the hotel rooms.