(2013·高考天津卷)It was not until near the end of the letter ________ she mentioned her own plan.

can you work this Sunday—________ I’ve been working for two weeks on end.

______ to improve thecooperation with other countries

In those days bikes were not ______ used because few people could afford (负担起) to buy one.

e looked up, he suddenly foundhimselfby agroup of teenagers,