aggravate, reinforce, increase, strengthen, intensify这一组动词都有“加强”的意思。

aggravate v.加重(负担、罪行、病情等)，使之恶化。

I hurt my foot, then aggravated it by trying to walk too soon.
我的脚受伤了，而过早的下地走路又加重了伤情。

reinforce v.增援，一般用于军队或警察的行动；(以添加材料等)加固。

A police officer saw three thieves robbing a bank and radioed to reinforce him.
一位警察看到三个盗贼抢劫银行，用无线电话要求增援。

increase v.指数量上的增加。

The number of people has been increased. 
人数增加了。

strengthen v.加强，巩固，增强，相当于to become stronger。

Exercising every day strengthens the heart. 
每天锻炼可以提高心脏的功能。

Competition, they believe, strengthens the national character rather than corrupt it.
人们认为竞争加强了民族性而不是破坏了它。

intensify v.使变得更强烈、剧烈，加剧，相当于to become more intense or intensive。

intensify colors 
加深色彩