7.下列表达式中( )首先进行的运算是 COS[] 。()
A#1 =#6-#3*COS[#4]/#2,
B#1 =#6*[#2+#3*COS[#4+#5]] ,
C#1 =#6/#2-#3*COS[#4] ,
D#1 =#2+#3*COS[#4*#5]] ,
E#1 =COS[#4]*#6/#2-#3 。
A#1 =#6-#3*COS[#4]/#2,
B#1 =#6*[#2+#3*COS[#4+#5]] ,
C#1 =#6/#2-#3*COS[#4] ,
D#1 =#2+#3*COS[#4*#5]] ,
E#1 =COS[#4]*#6/#2-#3 。