A client has sustained a right tibial fracture and has just had a cast applied. Which instruction should the nurse provide in his cast care（）

A. Cover the cast with a blanket until the cast dries.

B. Keep your right leg elevated above heart level.

C. Use a knitting needle to scratch itches inside the cast.

D. A foul smell from the cast is normal.

闭式电空阀当主要风道断开时表示电空阀（）

A、线圈得电

B、气路相通

C、线圈无电

D、气路一定有堵塞现象