题干
Beethoven is a very____ （著名的）musician .
I'm____ （紧张的）out because I can't find the way home.
My mother often____ (担心)about my father's health..
She likes to s____ e-mails at school.
Lily is very t____ , she'd like to have some water.
答案(点此获取答案解析）
famous,stressed,worries,send,thirsty
O4n－+5 I－→6R2+ +5IO3－+ 9H2O ，则RO4n－中n的值为