While building a tunnel through the mountain, ________.
举一反三
- While ______ a tunnel through the mountain, the workers discovered an underground lake. A: built B: to built C: being built D: building
- While building a tunnel through the mountain, ________. A: an underground lake was discovered B: there was an underground lake discovered C: a lake was discovered underground D: the workers discovered an underground lake
- ________from the top of the mountain, the building looks like a bird nest.
- The train passed （）a tunnel at night A: out B: onto C: through D: on
- This train is going（）the tunnel quickly. A: down B: through C: along D: i