X
R
Y
Z
W
A：Y元素的最高价氧化物的水化物是含氧酸中酸性最强的
B：W和R只能形成一种化合物WR3，且为酸性氧化物
C：X的最高价含氧酸与它的简单气态氢化物发生氧化还原反应
D：Z与R形成的化合物ZR2是生产光纤制品的基本原料
- What do you think of the dish I cooked for you?
- I haven't had it yet. However, it good.
(____) It's a programme about China.
(____) We've got lots of food.
(____) Thank you for talking to us.
(____) She couldn't read or write.
(____) He didn't have any legs then.
在我国四大地理分区中，处于我国地势第一级阶梯的是（ ）
I forgot to turn ______ the lights when I left.
