参考答案

正确答案：C
解析：occasionally与sometimes意思相近：有时，偶尔。I drink coffee only occasionally．我只是偶尔才喝咖啡。regularly：定期地，有规律地。The doctor told him to check his blood pressure regularly．大夫要他定期地查血压。accidentally：意外地，偶然地。I accidentally found the book I had been looking for．我偶然碰到我一直想要的书。successfully：成功地。We have completed the experiment successfully．我们成功地做完了实验。