答:5行共有20人.
根据句意和首字母提示,完成句中所缺单词①We should brush our____ (tooth) every day.②—What’s Jane doing? —She’s b____ her sister.③ What is she doing for v____ ?④—How do you come to school? —I usually ride a b____ to school.⑤ I want to s ____ an e-mail to my aunt.
如果 13 a=3b,那么a:b=____:____.(结果填最简整数比)