Lose one’s hair 脱发，掉发

【例句】
Goodness, I can t believe that I m starting to lose my hair. 　　
天哪，真不敢相信我竟然开始脱发了。 　　

When he was about thirty,he began to lose his hair. 　　
当他快30岁时，他就开始脱发了。