.
_________ it was to become was a mystery until the dust began to slowly combine into a ball moving around the sun.
| A．That | B．What | C．Which | D．Whether |
theirs
| A．thread | B．smooth | C．thirsty | D．health |
society
| A．achieve | B．friend | C．science | D．believe |
success
| A．official | B．excuse | C．correct | D．exciting |
—HaveyougottimeonFriday?
—________
| A．It'scertain. | B．Ofcoursenot |
| C．Why? I'llstayathome. | D．Youcansaythatagain. |
Some young people these days just ________ go out of their homes to contact the real world．
| A．mustn’t | B．won’t | C．mightn’t | D．shouldn’t |