________，John returned to school from his hometown.
| A．The summer vacation being over |
| B．The summer vacation is over |
| C．Because the summer vacation over |
| D．After the summer vacation being over |
Mike is a student at a famous university, _______ for a doctor degree.
| A．studied | B．studying | C．to have studied | D．to be studying |
There is a feeling in me _______ we’ll surely find a cure for Aids.
| A．that | B．which | C．of which | D．when |
.__________,we must believe in ourselves and believe that we can do something well.
| A．However life is difficult | B． However is life difficult |
| C．However difficult life is | D． However difficult is life |
In 1800s, a group of adventurers(探险家) ______ on their exploring trip. Five days later, they came to what is now known as Quebec.
| A．set up | B．set down | C．set about | D．set out |
---It’s said that no one ______ light a cigarette at a gas station.
--- Yes. Safety always comes the first.
| A．can | B．may | C．shall | D．must |