if (condition1) {statement...} else if (condition2) {statement...} else {statement...}

grade = 60

if (grade >= 90) {print "优秀"} else if (grade >= 60) {print "及格"} else {print "不及格"}

if (grade >= 90) {
    print "优秀"
} else if (grade >= 60) {
    print "及格"
} else {
    print "不及格"
}