表达式2: left parenthesis, cos left parenthesis, "t" , right parenthesis , sin left parenthesis, "t" , right parenthesis , right parenthesiscost,sint
2
表达式3: StartFraction, sin left parenthesis, 10 "t" , right parenthesis plus 4 Over 4 , EndFraction left parenthesis, cos left parenthesis, "t" , right parenthesis , sin left parenthesis, "t" , right parenthesis , right parenthesissin10t+44cost,sint