题目

Last weekend I went snowshoeing with a group of teachers from my school.    21   , it felt a little strange --- a bit like ,wearing flippers（脚蹼）   22    you swim! l felt quite clumsy to start with, and it was    23    to climb over the fallen trees with the snowshoes    24    to my feet. However, I love    25    and am used to walking in mountainous areas    26    I soon got used to it. I loved walking through the forest and seeing all the trees covered in    27   ! At times, walking uphill in the snow was hard,    28    when there 一定条件下，碳钢腐蚀与溶液pH的关系如下：pH2466．5813.514腐蚀快慢较快慢较快主要产物Fe2+Fe3O4Fe2O3FeO2- 下列说法不正确的是A．在pH＜4的溶液中，碳钢主要发生析氢腐蚀B．在pH＞6的溶液中，碳钢主要发生吸氧腐蚀C．在pH＞14的溶液中，碳钢腐蚀的正极反应为O2+4OH-+4e-=2H2OD．在煮沸除氧气后的碱性溶液中，碳钢腐蚀速率会减慢