英语：1.on10may ,LinTao was at home alone ,suddenly ,he heard s

英语：1.on10may ,LinTao was at home alone ,suddenly ,he heard someone shouting "fire,fire!"2.this morning i heard someone shouted"help ,help!"请问1,2两个句子意思一样,为什么第1个句子用shouting 而第2句用了shouted?3the 20-year-old boy called LinTao helped his neighbour out of a fire.请问helped out of 4.just at that moment the door opened and the teacher walked in.请问walked in能换成went in 5.doctor John walk to his hospital.同意句：doctor John （）（）（）to his hospital..