We regret to inform you that there are no tickets for Friday’s performance.A. availableB.

问题补充：

We regret to inform you that there are no tickets for Friday’s performance.

A. available

B. useful

C. convenient

D. affordable

答案：

(答案→)A. available

B. useful

C. convenient

D. affordable

解析：A.available可获得的，可买到的，B.useful有用的，C.convenient方便的， D.affordable 可负担得起的，句意：我们很遗憾的通知你星期五表演的票买不到了。所以选A。