45. They are dancing a dance on the New Year’s eve.
A.gay
B.excited
C.pleasure
D.Fun
答案:A
在整个人群中,男女比例基本相等的原因是: ( )
①男性产生X型和Y型两种精子,且比例是1:1,女性只产生一种X型卵细胞
②女性产生X型和Y型两种卵细胞,男性只产生一种X型精子
③男性产生的两种精子与卵细胞结合的机会相等
④女性产生的两种卵细胞与精子结合的机会相等
⑤含XX染色体的受精卵发育成女性,含XY染色体的受精卵发育成男性
A.①②③
B.②④⑤
C.①③⑤
D.③④⑤
—Why are you watching a football match?
—______ [ ]
A. It’s exciting.
B. I have a football.
C. I’m at home.
D. I watch football matches at night.