【单选题】下列关于构成生物体的化学元素的叙述中,正确的是 [ ]
A.
无机自然界中存在的化学元素在生物体内都可以找到
B.
含量占生物体总重量万分之一以下的元素称为微量元素
C.
组成生物体和组成无机自然界的化学元素中,碳元素的含量最高
D.
不同生物体内各种化学元素的种类大体相同,但含量相差很大
【简答题】从下面所给的词汇进行选择,将正确的序号( A, B, C.... )填入空格中。 (1) What a ____________ garden it is! (2) ____________ as she was, she never looked down the poor. (3) It is a ____________ day, the leaves have been blown o...
【简答题】How often one hears children wishing they were grown-ups and old people wishing they were young again. Each age has its pleasures and its pains, and the happiest person is the one who enjoys what each...
【简答题】移动闭塞的3个基本要素是( )、( )、目标点。
【简答题】选词填空,只填序号。 A. evening B. beside c. under D. library E. windy 1. The eraser is _______ the pencil. 2. We are reading a book in the _______. 3. I have supper at 7:00 in the _______. 4. The pen i...