参考答案

正确答案：C
解析：hold on to sth．原意为“抓住某物不放”，此处作“坚持下去”讲，如：We are determined to hold on to this plan no matter what difficulties we might run into．不管遇到什么困难，我们都下决心把这个计划坚持下去。hold up意为“使耽搁，使停顿”，不与to搭配，如：The building of the new road has been held up by bad weather．由于天气恶劣，修建新马路的