A:13
B:3
C:﹣3
D:﹣ 13
(3)班的50名同学进行物理、化学两种实验测试,经最后统计知:物理实验做对的有40人,化学实验做对的有31人,两种实验都做错的有4人,则这两种实验都做对的有( )
—We mainly ________ buyers from Europe and our products are well received.