______ medicine works in a human body is a question _______ not everyone can understand fully.
| A．How; that | B．That; which |
| C．That; which | D．What; that |
I was not __________ her presence till she spoke to me.
| A．aware | B．aware about |
| C．aware of | D．aware to |
People all over the country felt shocked __________ they heard of the news __________ eight children were killed at the school gate.
| A．the moment; that | B．when; which |
| C．immediately; / | D．the second; what |
I must apologize for __________ ahead of time.
| A．letting you not know | B．not letting you know |
| C．letting you know not | D．letting not you know |
You must __________ the key information in the text if you want to choose the correct answer.
| A．leave out | B．let out |
| C．make out | D．find out |
We are at your service. Don't ________ to turn to us if you have any further problems.
| A．beg |
| B．bother |
| C．intend |
| D．hesitate |