选D
这里做“了解; 认识到; 理解; 领会; 意识到 ”讲.
如：
If you were in the Sahara, you would realize the value of fresh water.
如果你在撒哈拉大沙漠, 你就会知道淡水的价值了.
Columbus had not realized that this new land was not India.
哥伦布当时还没有认识到这块新大陆不是印度.
They realized the situation to be against them.
他们意识到形势对他们不利.