1. crack a smile 展颜微笑，莞尔一笑

Definition: to smile, especially when you do not feel like smiling.

The man was willing to do anything to make his wife crack a smile. (为了让他的妻子展颜微笑，他愿意做任何事情。)

2. laugh a hearty laugh/laugh heartily 放声大笑，开怀大笑

Definition: to laugh loudly and uncontrollably

Upon hearing that he had won the lottery, the man laughed heartily. (知道自己中奖了，这个男人开怀大笑。)

3. force a smile 强作欢颜

Definition: to smile even though you feel sorrowful or unhappy

At the funeral, he forced a smile for anyone who offered condolences. (在葬礼上，他强颜欢笑面对前来吊唁的人。)

4. a saccharine smile 谄笑，谄媚的笑

Definition: a smile designed to please others

When he talks to his boss, he puts on a saccharine smile. (他跟老板说话的时候，满脸都是谄媚的假笑。)

5. smile bitterly 苦笑

Definition: to smile when you have no choice or can do nothing to help

The student smiled bitterly when his teacher caught him copying his homework. (抄作业被老师抓到后，这个学生满脸苦笑。)