39、ask for 要求
40、attach importance to 重視
41、pay attention to 重視 catch one's attention 引起…注意/重視
42、available可得/買到的
There is no ticket available.
43、average 平均on(the)
44、be aware of = realize 意識到 be sure 一定要，肯定
He apologized to us for the mistake as soon as he was aware of it.
Be sure not to be late for the meeting.
I'm sure the play will be a great success.
45、back up 支持
46、background 背景
47、base …on… 把…建立在…基礎之上
His article is based on the research.
48、bear 忍受，容忍同義詞：
endure tolerate stand put up with
She cannot bear to see the child in pains.
49、do/try one's best
He said he would try his best to carry out the plan.
50、because 連詞：There will be no meeting because the manager will be on the vacation next week.
because of 介詞：His wedding will be put off because of his father's death.