短周期元素X、Y、Z关系如图，X原子的电子层数为n，最外层电子数为2n。W原子最内层电子数是最外层电子数的2倍。下列说法错误的是
| X |
|
|
|
| |
|
Y |
Z |
A．X 和Y都是非金属元素，其中X最高化合价为+5价
B．X、W的最高价氧化物在一定条件下能反应
C．元素X、W和氧元素可形成化学式为W2XO3共价化合物
D．Y、Z的氢化物的稳定性：Y<Z
Progress______ so far very good and we are sure that the work will be finished on time.
| A．was | B．had been | C．has been | D．will be |
Charles was alone at home, with_______ looking after him.
| A．someone | B．anyone | C．not one | D．no one |
It is often ______ that human beings are naturally equipped to speak.
| A．said | B．to say | C．saying | D．being said |
I can’t leave. She told me that I ______ stay here until she comes back.
| A．can | B．must | C．will | D．may |
—— Do you mind my opening the window? It’s a bit hot in here.
—— ______ , as a matter of fact
| A．Go ahead | B．Yes, my pleasure |
C．Yes, I do | D．Come on |