下列金属中，金属活动性最强的是（    ）

“人间四月芳菲尽，山寺桃花始盛开”．造成这一差异的非生物因素主要是（  ）

阅读短文，判断下列句子是否正确。
    Ann went to Qingdao with her friends on her holiday. They went there by train. They went to the beautiful beach. The weather was sunny and hot. So they had great fun playing in the water.They ate lots of fresh fish for lunch. In the afternoon, they rode bikes. Jack fell off his bike and hurt his leg. So Jack stayed at the hotel and watched TV. On the second day, Ann took many pictures of the sea. And she bought some gifts for her parents. Anyway, they had a good time.

下列各项中，没有语病的一项是（   ）       

已知函数 $f\left(x\right)=3e^{\left|x-1\right|}-a\left(2^{x-1}+2^{1-x}\right)-a^2$ 有唯一零点，则负实数 $a=$ （    ）