非谓语动词The boy a blue jacket is John's brother.A.wear B.wore C.wearing D.wears

31.The boy (wearing) a blue jacket is John's brother.
选择 C.
现在分词作定语等于定语从句who is wearing a blue jacket的简化
32.(Spoken) English is quite different from written English.
选择A
(Spoken) English = English (which is spoken) (被口头说的英语,下文还有written English【书面英语】参照)
33.He is from an (English-speaking) country.
选择：B.
English-speaking = English which people speak (人们说英语)
34.(Having finished) their lessons,they went to the cinema.
选择：D.
(Having finished) their lessons = (after/when he had finished) their lessons（指先结束课后,后看电影）
(finishing) their lesson = (as he finished) their lessons （指一边结束课程一边去看电影）
35.(Knowing) he had won the first prize,he felt very happy.
选择：C.
(Knowing) he had won the first prize = (when/because he knew) he had won the first prize（他知道了赢得了头等奖的同时感到高兴）
36.As soon as she entered the room,the girl caught sight of the flowers (bought) by her mother.
选择：D.
flowers (bought) by her mother = flowers (which ws bought) by her mother （被母亲买回来的花）
flowers (being bought) = flowers (which were buying) by her mother （正被母亲买的花）
37.The old scientist has been invited to a party (to be held) next Monday evening.
选择：D
a party (to be held) next Monday evening = a party (which will be held) next Monday evening.（下周一将要举办的聚会）
a party (being held) next Monday evening = a party (which is been holdings he knew ) next Monday evening.（下周一正在举办的聚会——“下周一”和“正在”矛盾）
38.The building (being built) now will be used as our reading room.
选择：C.
The building (being built) now = The building (which is been building) now (此刻正在建造的大楼——进行时态的被动语态)
39.I advised (him to start) at once.
选择：B.（him 是宾语,不定式是宾补,表示advise以后进行的行为）
advise sb.to do sth.表示“建议某人去做某事”
40.You shouldn't allow (students to play) games near the classroom,for it's too noisy.
选择：C.
allow students to play games 表示“允许学生玩耍”,而allow playing games表示“允许任何人玩耍”.另外,allow 后不能用现在分词作宾补,即allow students to playing games.