下列人类活动中，可引起生态破坏的是[ ]
A、围湖造田
B、黄土高原上种草种树
C、内蒙古高原上退耕还牧
D、发电厂向大气排放烟尘
答案：A
商品流通企业销售费用不多的，可以将其并入“管理费用”科日核算。( )
This is _______ difficult problem that few students can work it out. [ ]
A. so
B. so a
C. such
D. such a
