Rice grown in the suoth of China（这句话漏了一个is）
改：People grow rice in the south of China.
trees are planed in spring every year（这句 planed 应该是planted）
改：People plant trees in spring every year.
these photos were taken on the Great Wall last year
改：Itook these photos on the Great Wall last year.
Can these books be taken out of the reading—room?
改：Can I take these books out of the reading-room?
japanese is taught in our school
改：Teachers teach us （students,个人倾向于用us）Japanese in our school
The flowers shuold be wanterd
改：We(或people) should water the flowers.
The room must keep clean（这句是被动语态把?The room must be kept clean）
改：We(同上) must keep the room clean.
When will the sports meeting held?（此句应也是被动语态,be held）
改：When will we hold the sports meeting?
He was seen to go out just now
改：I saw him go out just now.
This question may be answered in english
改：We may answer this question in English.