Among the following statements, which are true ones ?

A.After 1949, the Railway Ministry was founded to take full charge of railway construction and operation across the country.

B.In 1949, China started her first five-year development plan, including the enlargement and expansion of the railway network.

C.The emphasis of railway network development during first three decades of new China was on constructing new railway lines in the southwest and northwest of China.

D.After 1949, the main lines were restored and re-connected and the construction work was done massively.

正确答案：After 1949, the Railway Ministry was founded to take full charge of railway construction and operation across the country.；The emphasis of railway network development during first three decades of new China was on constructing new railway lines in the southwest and northwest of China.；After 1949, the main lines were restored and re-connected and the construction work was done massively.