某生物减数分裂产生四种配子;即Ab:aB:AB:ab=4:4:1:1,此生物测交,后代出现AaBb的几率是[ ]
A.1/4
B.1/10
C.1/5
D.2/5
答案:B
It's quite strange that the man sleeps with his mouth____ and his eyes _____.
A.closed; open
B.closed; opened
C.closing; open
D.closing; opening
一个国家发展旅游的动机一般包括()、()和经济三个方面。