It is reported that many a new house _____ at present in the disaster area. [ ]

A. are being built

B. were being built

C. was being built

D. is being built

下列有关生态恢复技术的内容阐述，正确的有( )。

A．选择合适的植物种类改造生态系统的生长介质，使之变得更适合植物的生长

B．利用物理的或化学的方法直接改良介质，使之能够直接进行生态恢复

C．在被酸沉降所酸化的地区，施加一定量石灰快速改变土壤的pH值是生态恢复的必要手段之一

D．垃圾填埋场的生态恢复要解决的关键技术问题是填埋气体的排导问题