The crowded population and busy traffic make people concern about the city.
I can't help but think of the days that I had in school.When I see this photo,I can't help but remember the days which I was in school.可以嗎？When I see this photo,I can't help but remember the days which I was in school.這個把was改成had或者spent就可以了。因為days是名詞，I was days，不符合邏輯。第一個的話，你嘗試了主語從句，但是并不正確。因為你用主語從句的同時，有用到了which引導(dǎo)定語從句，結(jié)果就是主語從句缺少謂賓成分，建議改成：That the traffic is over crowded with people and is so busymakes people have more concerns on this city.