身穿红、黄两种颜色衣服的各有两人,现将这4人排成一行,要求穿相同颜色衣服的人不能相邻,则不同的排法共有. [ ]
A.4种
B.6种
C.8种
D.16种
答案:C
— You look tired, you should have a good rest for _______ days.
—That sounds good.
A.a few
B.few
C.little
D.a little
心脏瓣膜病并发亚急性细菌性心内膜炎,当心内膜赘生物脱落引起周围动脉栓塞时,最常见的是
A.脑动脉栓塞
B.肾动脉栓塞
C.肺栓塞
D.皮肤黏膜栓塞
E.视网膜动脉栓塞