She does not know if he is alive or dead.

她不知道他是活还是死。

《柯林斯英汉双解大词典》

If the organic material decays or is oxidized, it will not form petroleum.

如果有机物腐烂或氧化，它不会形成石油。

《柯林斯英汉双解大词典》

If you suspect a gas leak, do not strike a match or even turn on an electric light.

假如你怀疑有煤气泄漏，不要划火柴，甚至连电灯都不要开。

《牛津词典》

In a poker game you do not want to let your opponents know if your cards are good or bad.

VOA: special.2009.11.22

So, that's a homogeneous system, one phase. You have to know if your system is an equilibrium system or not.

所以这是个均匀系统，只有一个相，你得知道你的系统,是不是个平衡系统。

麻省理工公开课 - 热力学与动力学课程节选

Things can't become holy and can't come into contact with the holy or the sacred if they are not first pure.

事物不可能变得神圣或是与神圣有联系,如果它们连纯洁都算不上。

耶鲁公开课 - 旧约导论课程节选

In the U.S. I can easily try out a new employee and see if they work out or not.

FORBES: This is a guest post by Magatte Wade

The U.N. says "there's no way to tell" if these vehicles were used in the abduction or not.

CNN: U.N. to probe handling of Lebanon video

They would know where they stand. and If they should invest in their business, or not.

FORBES: Guest Post: Eliminate Fraud and Waste