问题
选择题
火山爆发产生的火山灰里含有大量的硅酸钙(CaSiO3),硅酸钙中硅元素的化合价为( )
A.+3
B.+4
C.+5
D.-4
答案
答案:B
火山爆发产生的火山灰里含有大量的硅酸钙(CaSiO3),硅酸钙中硅元素的化合价为( )
A.+3
B.+4
C.+5
D.-4
答案:B
Lucy: Sorry. I haven’t. You may ask Linda. _______小题1:____________ Dick: Excuse me, Linda. Have you got a dictionary? Linda: Yes. ______小题2:________. Dick: Thank you so much. I’ll give it back to you soon. By the way, tomorrow is my birthday. _______小题3:___________. Linda: Yes, I’d love to. __________小题4:_____________. Dick: About seven o’clock. Linda: I’ll try to be there on time, but __________小题5:________. Dick: It doesn’t matter. Work must come first. |