【单选题】A 、 B 、 C 、 D 、 E 为原子序数依次增大的短周期元素, A 、 B 、 E 的最外层电子数之和为 17 ,质子数之和为 31 ,若 E 不为主族元素, B 的气态氢化物的水溶液显碱性, C 元素在大气中存在两种常见单质, D 位于第三周期,且原子最外层电子数是次外层电子数的 0.875 倍,下列叙述正确的是 ( )
B.
原子半径的大小顺序: r (A)> r (B)> r (C)
C.
D 的非金属性强于 A ,所以 D 的含氧酸的酸性强于 A
D.
含有 A 、 B 两元素的盐溶液不可能显中性
【判断题】Marina měla problémy s bytem.
【单选题】In the letter Shelia talked about________ possible reasons(原因) for Alice's probl
A.
28. In the letter Shelia talked about________ possible reasons(原因) for Alice's problems. A. four
【单选题】“____ everyone&39;s here, ” she said, “let&39;s begin to discuss the solution to the problems we have found."
【单选题】普通V带轮设计时,轮毂的长度L应根据 来确定,轮缘宽度应根据 来确定
【单选题】If such unhappy people don't change their bad behavior, the author's solution to the problem is that ______.
A.
people should avoid contact with them
B.
people should criticize their misconduct
C.
people should help them recognize the bad effects of the habit
D.
people should show no respect and politeness to them