肺泡适于与血液进行气体交换的特点是:
A:肺泡数量多
B:肺泡外有丰富的毛细血管
C:肺泡壁薄
D:以上都是
选出句子正确的答语。
① How old is he? ____ A. I'm 1.58 metres.
② How heavy are you?____ B. He is five years old.
③ How tall are you? ____ C. I'm 45 kilograms.
④ Are you taller than me? ____ D. They're size 38.
⑤ What size are your shoes?____ E. Yes,I am.
绕____ 缓____ 锦____ 直____
饶____ 暖____ 绵____ 置____
山羊的毛色有白色和黑色,技术人员让多只白色公羊与白色母羊交配繁殖,进行毛色遗传实验,并将子代毛色数据绘制成柱形图,请分析作答: