缺氧引起呼吸加深加快的原因是
A．刺激呼吸肌
B．刺激外周化学感受器
C．刺激中枢化学感受器
D．通过肺牵张反射
E．直接刺激呼吸中枢
参考答案：B
(2013·福建，34)Not until he went through real hardship ________ the love we have for our families is important.
A．had he realized
B．did he realize
C．he realized
D．he had realized
党的十一届三中全会以后，农村改革的发展方向有
①专业化②商品化③社会化④承包化[ ]
A．①②
B．①②③
C．②③④
D．①②③④
