想知道硬币上有无细菌，比较可行的检查方法是（  ）

根据句意，用括号中所给单词的正确形式填空。
①The new students had always lived with their parents before they came here. They are not used to____  (be) away from home.
②Antonio is liked by everyone because he is always ready ____ (help) others.
③Teenagers should ____  (allow) to go out with their friends.
④We hope the weather will be fine, but it is getting even____ (bad).
⑤He believed his lucky number was 12, so he decided to live on the ____  (twelve) floor.
⑥Timmy has spelt the name____  (correct). That’s why his friend can’t find him easily.
⑦I wonder if there are any____ (suggest) about how to learn English well.

在数列{a_n}中，a₁=1，a_n+1= $\frac{a_n}{1+a_n}$ （n=1，2，3，…），