请根据括号中的中文提示、英文释义或句意,写出句中所缺单词,使句子通顺。
We should take action to (减少) the pollution.
Jack (娶) Mary in 2000.
Now the student has begun to (get to know and understand ) that he was wrong.
He’s planning to travel (to or in a foreign country ), but he can’t decide which country to go.
Not all snakes are harmful. Some snakes are .