用定语从句完成下列各句
问题描述：
用定语从句完成下列各句
1、He joined the PLA in 1946__________________.(他的家乡解放时）
2、Last night we met the old scientist _____________.(我们早就希望会见的）
3、The building _________________（矗立在河那边的）is a hospital.
答
1、He joined the PLA in 1946 when his hometown was liberated.
2、Last night we met the old scientist who/whom we wanted to visit much earlier.
3、The building which stands by the side of the river is a hospital.