1. —How about having a picnic with me ?
—I’d love to, _______ I’m afraid I have no time.
A. so B. and C. but D. because
2. We didn’t start our discussion _______ everybody arrived.
A. since B. if C. while D. until
3. You may easily lose your way in Shanghai _______ you don’t have a map or a guide.
A. until B. unless C. though D. if
