问题
We were told that ______ when Marx was already _______, he started to learn Russian.
A:in 1840’s; in his fifties
B:in the 1840’s; his fifties
C:in the 1840’s; in his fifties
D:the 1840’s; in his fifties
B:in the 1840’s; his fifties
C:in the 1840’s; in his fifties
D:the 1840’s; in his fifties
正确答案是：
