is kept是什么时态

　　All our glass and China is kept in the cupboard.

　　我们所有的.玻璃器皿和瓷器都放在碗橱里。

　　For reasons of security the door is always kept locked.

　　为了保证安全，门总是锁着的。

　　The suspect is being kept under observation.

　　嫌疑人正受到监视。

　　A skeleton staff of 20 is being kept on.

　　留下了20名骨干人员。

　　Next year's collection is still being kept under wraps.

　　明年的时装系列仍在保密之中。