weak用作形容词使用，有虚弱的，无力的，(器官或感官)功能差的，受损伤的，声音或笑容)微弱的，不热情的等含义。

1.虚弱的，无力的

I was too weak to move or think or speak...

我太虚弱了，无法动弹，无法思考，也无法说话。

His arms and legs were weak.

他的四肢虚弱无力。

2.(器官或感官)功能差的，受损伤的

Until the beating, Cantanco's eyesight had been weak, but adequate...

挨打前坎坦科的视力就一直很弱，不过也还勉强看得见。

She tired easily and had a weak heart.

她很容易疲劳，心脏也不好。

3.意志薄弱的;懦弱的

He was a nice doctor, but a weak man who wasn't going to stick his neck out...

他是位为人和蔼的医生，但胆小怕事，不敢冒什么风险。

You have been conditioned to believe that it is weak to be scared.

你已经习惯性地认为害怕就是软弱。

4.(声音或笑容)微弱的，不热情的，无力的

His weak voice was almost inaudible...

他的声音微弱，几乎听不见。

He managed a weak smile.

他勉强挤出一丝笑容。

5.不牢固的

Flours with strong gluten absorb more water than do flours with weak gluten.

含有强有力的面筋的面粉较含有不太牢固的面筋面粉要吸收更多的水分。

The structure will prove weak in service.

该构件在使用中将被证明是不牢固的。