根据句子意思，用括号中所给词的正确形式填空，每空填一词。

1. English dictionaries are very ______ (use) to you when you study English.

2. Could you pass the ______ (knife) to me? We need them to make pumpkin lanterns.

3. Don't be ______ (patient)! You should listen to what he is saying first.

4. Four ______ (five) of the students in our class have heard about the trip.

5. The guide has collected all the ______ (visit) ID cards.

设有下列的程序段：
char str[]="Hello";
char*ptr;
ptr=-str;
执行上面的程序段后，*(ptr+5) 的值为______。