下面关于SLIP、PPP、SDH/SONET描述真确的是（）。

pre pared to be frightened. Only the fact that she was going to meet her son who she had not seen for three years had given her the courage to make the flight.

She sat in her seat, her hands gripping its arms, her seat belt already fastened. The air hostess was talking, telling everyone what to do in case of emergency, showing them where their .life-jackets were. The plane was crowded, every seat was full. From her window seat, getting out in a hurry would be impossible, thought Ann. In any case who would want to get out of a plane in mid-air？

The engines began to shake--the noise increased till it was like a great rushing wind. She looked out to see the runway slip past at astonishing speed. She wanted to cry out--to stop the plane before it left the ground, but she knew she was trapped in this great roaring machine. I must scream, she told herself, and put her hands over her eyes.

There was a strange feeling as if she were going up in a lift. The noise died down. Carefully she opened her eyes. Through the window she saw a great carpet of cloud above, so beautiful that she stared in wonder, hardly turning away from the window till they touched down.

Ann thought she would be frightened because ______.

A．she had never flown before

B．she had a fear of being in high places

C．she hadn' t made proper preparations.

D．she was naturally timid

"Pepys slipped on his dressing gown". To slip on means______.

A．to be wearing

B．to be pushing

C．to take off

D．to put on

A.stumbled

B.slip

C.blundered

D.crept

A. be put up

B. give in

C. be turned on

D. go out

A.errors

B. mistakes

C. fault

D. slip

A、pull down

B、slip away

C、fall apart

D、end up

E、stir up

It was a toy plane ______ John bought for his son yesterday.

A．what

B．who

C．that

D．why

A.of

B.to

C.off

D.away

Mother hopes her son will ______ doing anything rash.

A．keep from

B．avoid from

C．ask from

D．protect from

The______ in my son's clothes are beginning to come apart.

A．seams

B．beams

C．rims

D．segments