例句與造句

1. but why is availability an issue in today's packet networks that deliver atm, frame relay or ip services
   但是為什么在今天提供atm、幀中繼或ip服務的包交換網(wǎng)中可用性成了一個問題？
2. It's difficult to find availability a in a sentence. 用availability a造句挺難的