在男性和女性生殖系统中,能产生精子和卵细胞的性器官分别是( )
A:阴茎、子宫
B:阴茎、卵巢
C:睾丸、卵巢
D:睾丸、子宫
已知x=3+1,y=3-1,求下列各式的值
(1)x2+2xy+y2 (2)x2+y2﹣5xy.
After his journey from abroad, Richard Jones returned home, ______ .
How about____ (go) for a walk in the park?