Modal verbs generally take the bare infinitive.

情词通常用不带to 不定式。

The heavy rain might settle the changeable weather.

这场大雨也许能使变幻不定天气稳定下来。

A gust of wind blew the flickering candle out.

一阵风把闪烁不定蜡烛吹熄了。

He has an incalculable disposition.

他有一种捉摸不定脾气。

In dealing with that unpredictable man, you simply cannot follow a prearranged plan, you have to play it by ear.

和那个捉摸不定打交道, 你简直无法按预定计划事, 只好随机应变。

It's difficult to find a window cleaner who will call regularly—they all seem to be here today and gone tomorrow.

要找一个能定期上门来擦窗户很难——他们似乎都是些踪不定。

He accused me of being a tax-and-spend liberal, a Jimmy Carter clone, and a waffler who couldn't make up his mind.

他指责我是一个只知道增加税收和开支自由派，是第二个吉米.卡特，墙头草，一个举棋不定。

Trees of the family Dipterocarpaceae dominate the canopy and emergent layers of the hyper-diverse, aseasonal, humid lowland tropical forests of Southeast Asia.

龙脑香科植物为主东南亚热带雨林有一非常特别现象，那就是不定期大开花现象。