根据句子意思，用括号中所给单词的适当形式填空，
1 If you don’t tell me what the problem is, I can’t (help) you.
2 Miss Li is a kind teacher and she always talks to us (gentle).
3 The teacher told us that the gravity on Mars (be) only about three-eighth of that on Earth.
4 Mr Black has been in China for three years and now he is used to (eat) Chinese food.
5 The Eiffel Tower, a cultural icon of France, was completed at the end of the (nineteen) century.
6 It is worth (mention) that Nanjing has entered Top 10 Appealing Chinese Cities.