1.多出来一张20元的纸币 there is an extra twenty dollar bill

2.一张百元大钞 a hundred dollar bill

3.忘于做某事 forgot to do something

4.辅导员 counselor

5.一封信的摘录 a letter's synopsis

6.讲课费 lecturing fee

7.保持镇定 remain calm

8.迫使某人做某事 force someone to do something

9.登记;列入 register

10.如有必要的话 if it's absolutely necessary