a demand for sth.　对......的需求

supply and demand　供求

①He demanded ________(tell) everything.

②They demanded she ________(go) there together.

③This is a demanding job which ________(demand) patience.

2. opportunity，chance

这两个名词都有"机会"的意思。

①opportunity一般指有利的机会，chance指的机会可能有利，也可能不利，两者后接不定式或of＋doing。如：

He has a chance/opportunity to see the Premier.

＝He has a chance/opportunity of seeing the Premier.　

②chance有"可能性"的意思，opportunity则没有。

有可能做　There is a chance/possibility of sb. doing

＝There is a chance/possibility ＋that从句

＝(The) Chances are that...

③take this opportunity意为"趁此机会"；

take a chance＝take chances意为"冒险；投机"。

④chance可用作动词，opportunity则不能。如：

I chanced to see our old headmaster in the street some days ago.

3. decline，refuse，reject，deny

decline意为"婉谢"(客气礼貌)；还可意为"下降；衰落"；refuse意为"拒绝"(中性词)；reject意为"断然拒绝"(强烈坚决)；deny意为"否认；拒绝给予"。

从用法上看：

decline和refuse后接不定式to do，reject后一般不接不定式。deny意为"否认"时，后接动名词；表"拒绝给予某人"的搭配为deny sb. sth.或deny sth. to sb.。

on the decline＝in decline＝decline　在衰退