检索选修课程“C2”的学生中成绩最高的学生的学号。正确的SELECT的语句是 Ａ) SELECT S# FORM SC WHERE C#=“C2”AND GRADE＞=(SELECT GRADE FORM SC) WHERE C#=“C2”) Ｂ) SEIECT S#FORM SC WHERE C#=“C2”AND GRADE IN(SELECT CRADE FORRM SC) WHERE C#=“C2” Ｃ) SEIECT S# FORM SC WHERE C#=“C2”AND GRADE NOT IN(SELECT GRADE FORM SC WHERE C#=“C2” Ｄ) SEIECT S# FORM SC WHERE C#=“C2”AND CRANDE＞=ALL(SELECT GRADE FORM SC WHERE C#=“C2”)

高架绝缘斗臂车操作人员应服从（）的指挥，作业时应注意周围环境及（）速度。