胚胎期参与造血的器官有（）
A.骨髓
B.肝脏
C.胸腺
D.脾脏
E.淋巴结
参考答案：A, B, C, D, E
以下哪些部位不易发生淋病：
A．结膜B．咽腔C．直肠D．膀胱E．前列腺
A sea anchor is（）.
A.a heavy anchor with an extra long line used to anchor in deep water
B.a cone shaped bag used to slow down the wind drift effect
C.a padeye to which the sea painter is made fast
D.made of wood if it is an approved type
