关于to do与to be done刚才看了两个例句,给分析下什么时候用to do 什么时候to be doneany type of physical activity you choose to do will increase the number of calories your body uses.when the policemen arrived on the scene,torn pieces of paper were everywhere to be seen

to do 不定式，这里choose to do 表示主动，选择去做某事
to be done是被动式， to be seen这里表示被看见
希望对你有帮助哦~

to be done是被动啦，主语一般是物了。 to do 一般是固定句型里面的.

to do 是主动语态,一般是sb to do sth.
to be done是被动语态,是sth.to be done (by sb.)

to do sth为不定式的主动式，表示主动含义，这里any type of physical activity you choose to do中，you为to do 的发出者，故是主动的。
torn pieces of paper were everywhere to be seen中torn pieces of paper 为see的承受者，故是被动的，因而用被动式。