下列各句中，加点的成语使用恰当的一项是

“我无须对诸位说：世界局势很是严重……我们的政策不是反对任何国家、任何主义，而是反对全人类共同的敌人——饥饿、贫穷、绝望和混乱……美国政府能够尽力缓和局势，协助欧洲走上复兴道路。”与材料直接相关的是（    ）

阅读上面短文，然后判断句子正( A )误( B)。
     A man saw a boy standing beside a lake with a mirror (镜子).“Excuse me,” he said, “but could you tell me what you're doing?”
   “I'm fishing.”
   “With a mirror? Could you tell me how it works?”the man asked.
   “OK, but I want five dollars.”
     The man wanted to know the secret very much, so he handed the boy the money.“Now show me how it works,” he said. “Well”, the boy began, “you hold (拿) the mirror towards the water, and when a fish goes by, the sunlight in the mirror gives him a surprise. He stops and doesn't know what to do, and then you catch him at once. ”The man was surprised, “Can you really catch fish with the mirror? How many did you catch?”
   “You're the fifth today!” replied the boy.

两个大小相等的共点力T₁、T₂，当它们之间的夹角为90°时，合力F₁的大小为100 $\sqrt{2}$ N．求当它们之间夹角为60°时的合力F₂的大小．

如图所示是一款超市购物车，要求盛物框在承载60kg情况下，购物车的各部分不会严重变形和损坏。请对该购物车进行技术试验，并回答问题。