下列选用的除杂试剂和实验操作都正确的是（括号内为杂质）（ ）
| 选项 | 物质 | 除杂试剂（足量） | 操作方法 |
| A | CO2（HCl） | 氢氧化钠溶液 | 气体通过盛有烧碱溶液的洗气瓶 |
| B | NaCl（Na2CO3） | 盐酸 | 加入足量盐酸、蒸发、结晶 |
| C | MnO2（NaCl） | 水 | 加足量水溶解、过滤、洗涤、干燥 |
| D | Cu（CuO） | 氧气 | 通入足量氧气并加热 |
BC
A、CO2中混有HCl气体，选用氢氧化钠溶液，把两种气体都吸收了，不符合除杂质的条件，故选项错误；
B、NaCl中混有Na2CO3，加入足量的稀盐酸，Na2CO3与稀盐酸反应生成氯化钠和水和二氧化碳，因此得到的是氯化钠溶液，然后蒸发、结晶即可，故选项正确；
C、MnO2中混有NaCl，二氧化锰不溶于水，氯化钠易溶于水，因此可以先加足量的水溶解，然后过滤、洗涤、干燥即可，故选项正确；
D、Cu中混有CuO，如果通入氧气加热，反而把原物质铜反应了，都成了杂质氧化铜，故选项错误．
故选BC．
| 完形填空 | ||||
| It was on a winter morning, near Oxford, Maryland, that I set the breakfast table beside the huge window, which __ 1__ the Tred Avon River. The snow decorated the shore in white. For a moment I stood quietly against the bookcase, appreciating what the night's snow had __ 2__. 3 I leaned forward and peered (盯着看) close to the frosted window. "It really is!" I cried out loud. "There is a goose out there!" I __ 4__ to the bookcase and pulled out a pair of binoculars (望远镜). Into their sights came the __ 5__ of a large Canada goose, very still, its wings folded tight to its sides, its __ 6__ frozen to the ice. Then from the dark sides, I saw a line of swans. They crossed __7__ the west of the broad river, moving __ 8__ to the east. As I __ 9__, the leader swung to the right, and then the white __10__ of birds become a white circle. It floated from the top of the sky downward. At last, as easy as feathers coming to earth, the circle __11__ the ice. The swans __12__ the frozen goose! Amazingly, those bills (啄) began to work on __13_. The long necks were lifted and curved down, __14__. It went on for a long time. At last, the goose was free and __15__ its big webbed (有蹼的) feet slowly. The goose __16__ its wings as far as they would go. The swans took off and __17__ on their eastward journey, in perfect formation, to their secret destination. __18__ them, rising with incredible speed and joy, the goose moved into the sky. I watched them __19__ they disappeared over the tips of the farthest trees. Only then did I realize that tears were running down my cheeks. This is a true story. I do not try to interpret it here. I just often __20__ it in the bad moments, and tell myself, "If so for birds, why not for man?" | ||||
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