1. 表示“决定做某事”，其后要接不定式，不能接动名词。如：

They decided to delay the meeting. 他们决定把会议推迟。

She decided to call his office. 她决定给他办公室打电话。

若要接动名词，应先接介词 on（但不如用不定式结构常见）。如：

We decided on leaving. 我们决定离开。

He decided on going abroad. 他决定出国。(www.yygrammar.com)

另外，decide on之后还可接名词或代词，表示“对……作出决定”或“选定……”。如：

We haven’t decided on a price but we’re open to offers. 价钱未定，欢迎顾主开价。

After seeing all the candidates we’ve decided on this one. 我们见了所有的候选人，决定选这位。

2. 表示“决定不做某事”，可用 decide not to do 或 decide against doing。如：

He decide not to change [against changing] his job. 他决定不换工作。

They have decided not to move [against moving] to London. 他们已决定不搬到伦敦去。

另外，decide against 之后也可接名词或代词。如：

After talking the matter over, they decided against the plan. 经过反复讨论，他们决定不采用该计划。