外痔，脾虚气陷证
A．凉血地黄汤B．止痛如神汤C．桃仁承气汤D．补中益气汤E．当归四逆汤
参考答案：D
It was when I arrived home _____ I realized I had left my bag in the library.
A．what
B．because
C．that
D．until
外胚层细胞在（）诱导下，形成神经板。
