中胚叶造血期首先形成血岛的是以下哪个组织（）
A.卵黄囊
B.胸腺
C.骨髓
D.肝脏
E.脾脏
参考答案：A
It makes no________which road you take；both lead to the city，and they are equally long.[ ]
A．point
B．sense
C．matter
D．difference
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