题干
____is known to all, good friends _________ happiness and value to life.
A：It; add
B：As; add
C：It; add up
D：As; add to
答案(点此获取答案解析）
B
____is known to all, good friends _________ happiness and value to life.
A：It; add
B：As; add
C：It; add up
D：As; add to
