染色标记法编号的方法通常是（）。
A.不分左右，上下不拘
B.先左后右，先上后下
C.先右后左，先下后上
D.先左后右，先下后上
参考答案：B
十烦恼
Could you finish the task in two days? 一（）I have something else to do these days．
A.I could not
B.Yes．I think so
C.I'm afraid so
D.I'm afraid not
