A:21:5
B:11:3
C:1:4
D:4:1
如图,已知:AB∥CD,CE分别交AB、CD于点F、C,若∠E=20°,∠C=45°,则∠A的度数为( )
-I didn't hear you come just now.
-That's good. We tried __________ any noise, for you were sleeping.
防止污染、保护生物圈是人类与自然和谐发展的必然选择,下列做法错误的是( )
下列物质间的转化不能一步实现的是( )
下列物质与用途对应关系错误的是( )