— Good morning, Li Ming.
— ______________[ ]
A. Good-bye, Tom.
B. Good morning, Tom.
答案:B
-- Did the door-keeper let you in?
-- No. __________ I tried to tell him that I was your cousin, he just didn't believe me.
A.Regardless of
B.Whether
C.Even if
D.Even though
一束光由空气射入某介质时,入射光线与反射光线间的夹角为90°,折射光线与反射光线间的夹角为105°,则该介质的折射率及光在该介质中的传播速度为 ( ).
A.,c
B.1.2,
C.,c
D.,