中三電腦程式問題

指出以下程式的錯處:
1. 找出由寶林至北角港鐵單程票應繳付的款項：

var type; fare;

type = prompt( );

if(type = 成人){

fare = =9.5;

} else {

fare = 4.8;

}

alert(fare);

2.找出會考等級（A,B,C,D,E,F,U)對應評語：

var grade;

grade = prompt( );

if(grade = A){

comment = 'Distinction';

}

if(grade = = 'B' && grade = = 'C'){

comment = = 'Credit';

}

if(grade > 'D' and < 'F') {

comment= 'Pass';

}else{

comment = 'Fail';

}

alert ('comment');