1. I was born weak.I usually have stomachaches and backaches.
    我天生虚弱,我常常会胃痛和背痛.

2. It was not the sort of bright yellow sun making everything lift up at the edges, almost in fear, that I was used to, but a pale yellow sun, as if the sun had grown weak from trying too hard to shine; but still it was sunny.
    这不是那种我所习惯的、使每一样东西的边缘几乎是颤巍巍地向上翘的那种金黄色的太阳，而是那种淡黄的、好象是一个因过分卖力地想发出灿烂的光芒而变得软弱无力的太阳，但它毕竟也是灿烂的。

3. In the third and final stage, people often feel weak, tired, and out of breath — and exercise performance is severely compromised.
    在第三也即最后阶段，人常常感到虚弱，疲乏无力，喘不过气，运动成绩大打折扣。