Question

there is( )"s"and( )"u" in the world bus. （ ）the evening of july 1st

Answer 1

there is( an)"s"and( a)"u" in the world bus.在单词bus里有一个s和一个u.读音为元音前用an，辅音前用a
（on ）the evening of july 1st 在7月1日的晚上.具体的某一日前用on

Answer 2

填 an ,a, on1. 不定冠词用an或者a，是根据它后面的单词是不是以元音音素开头。2.具体某天的上下午，晚上用介词on

Answer 3

填 an ,a, on.