-Should be fine.
如果順利拿到,我不用等幾個月;如果拒簽,我是否還可以用F1回來?
-After your F-2 visa application is denied, you have to go back to China from Canada directly if you don't have an F-1 visa stamp on your passport.
聽說30天之內不用簽證也可以回來的。
-It does not apply to the case when your visa application denial in Canada. If you don't apply for a visa there, you can come back to US using your previous F-1 I-94 even if you don't have an F-1 visa stamp. If your F-2 visa is approved, you can use the F-2 visa to enter US to get the F-2 status/I-94.
謝謝!