Lily enjoys _______ a film at the weekend.
考查enjoy doing sth.的固定搭配。
句意：莉莉喜欢周末看电影。enjoy doing sth.意为“喜欢做某事”，enjoy后若跟动词，只能跟-ing形式，故答案为C。
—She is too busy to help us to finish the work.
—Let's do it _______.
本题考查反身代词的用法。
根据本题语境以及us和Let's可知，此处表示“我们自己”，所以要用ourselves。