根据句子的意思,用“a,an,the或/”填空.
1.This is______"F" in 26 letters.
2.We had a walk by the river for____ hour yesterday evening.
3.There is not _____"U" in this word.
4.I have_____hat._____hat is new.
5.I often watch TV at_____seven in_____ evening.
6.—Where is my pencil?
— It is in ____ bag.