题目

    Children with autism(孤独症)have difficulty with social skills and communication．They often behave in limited and repeated ways and have what seem like unusual Strong interests．     Autism is more common in boys than girls．What causes it is not clear. Scientists are studying genes and possible environment influences．     Doctors usually cannot confirm a about three years old .Rebecca Landa  is diagnosis of autism until a child is a researcher at the Kennedy Krieger institute and Johns Hopkins University School of Medicine in Maryland .Professor Landa wanted to晋江地区排放到空气中的气体污染物主要是（　　）A．二氧化碳、氮气、一氧化碳B．甲烷、一氧化碳、二氧化氮C．二氧化硫、二氧化氮、一氧化碳D．一氧化碳、二氧化硫、二氧化碳