从使用情况来看，闭胸式的使用比较广泛。敞开式盾构之中有挤压式盾构、全部敞开式盾构，但在近些年的城市地下工程施工中已很少使用，在此不再说明。 高二英语句型转换练习 1.No matter what the circumstances are, we must stick to our post. _ _ _, we must stick to our post. 2.Not until I came back did he leave. _ _ _ _ I came back _ he _. 3.- I hear that Mr. Wang got injured in the accident and has stayed in hospital for some days. - _ _, lets go and visit him.keys: Whatever the circumstances 2. It was not until;that left 3. If so从使用情况来看，闭胸式的使用比较广泛。敞开式盾构之中有挤压式盾构、全部敞开式盾构，但在近些年的城市地下工程施工中已
