–Why has Tom looked unhappy recently? –He has some difficulty ______ with his new classmates at school.

—Have you________ Betty yet?—Not really．She won’t forgive me for having told her lies．

The box is so heavy that he cannot lift it. _______, he is only a ten-year-old child. 

With the stress heavier, physicians are always ______ caution upon citizens in view of heart attack.

This picture was taken a long time ago. I wonder if you can 　　　 my mother.