— These problems are too hard to . Will you give me some advice? — There are many ways. The most important is to have a careful plan.
A:hand out
B:work out
C:look out
D:break out
以外向型为主要特征的是( )
模:mú____ mó____
圈:quān____ juàn____
畜:chù____ xù____
行:xíng____ háng____
如图表示人体胸廓容积的变化,到b点时,肺泡内,呼吸道,外界气压的关系是( )