we must be careful when we cross the street.是什么从句?when 后面为什么不是现在进行时?

We must ___(be) careful. We must be careful.怎么改祈使句 So we must be careful when we use the Internet. It's ___(ice).We must be careful. you must be careful We must be careful with strangers.（划线部分提问）---- ---- we be carefulwith? When the fire d----- is high,we must be careful.We must not have c--- in the countryside.We must put our rubbish bin.At home ,we must not cook w--- an adult,We must not play near a fire ,It's everyone‘s job not to s----- a fire.首字母填空 We must be careful when we play sports. 变为一般疑问句 We must be very careful when we go across the m___ road must be,all,fires,we,careful,and,never,start连词成句 We must be careful when you go _____（cross） the road. we must be careful () fire 是用介词,用by对么?请问填什么. when _a diary ,we must be careful about what to write down是个完形填空 we must be careful with electricity 对划线部分提问划线的是electricity Something unusual seems ____,so we must be more careful,(happen) you must be careful改为祈使句 You must always be careful with it . You must be _(careful) than before.