1. This would solve the problem of ventilation, for if a train entered this tunnel, it would draw in fresh air behind it.
    这样就可以解决通风问题，因为如果一列火车开进隧道，它后面就会带进新鲜空气。

2. This would solve the problem of ventilation, for if a train entered this tunnel, it would draw in fresh air behind it.
    这样就解决了通风问题。因为如果有列火车开进隧道，它就把新鲜空气随之抽进了隧道。