travel可數嗎

　　They travel at speeds of up to 30 knots.

　　他們以高達30節的航速行進。

　　Our travel plans are still up in the air.

　　我們的旅行計劃尚未決定。

　　You can book at your local travel agency.

　　你可以在當地的旅行社訂票。