[問題]新東方-聽力test3 Q15

[elizabeth88]

M:Hey, Betty, you know I've been trying to get help with my physics. My friend recommended Gregory for a private tutor. Any thoughts?
W:Well, you could do a lot worse. Gregory's no slouch at physics.
What is the woman's opinion of Gregory?
A)Gregory is good but his major is not physics.
B)Gregory is not a good choice.
C)Gregory is very good at physics.
D)Gregory is good but he's not the best.
ANS:C
請問一下,紅色字是什麼意思?是假設語氣嗎?