Having a trip around the country is certainly good for the old couple, but it remains______ whether they will enjoy it.
【正确答案】
B
【答案解析】解析：本题考查固定用法。it remainsto be seen为固定用法，意思为“尚不确定，说不准”，but后面的分句是一个含有主语从句的复合句，it为这一复合句的形式主语，真正的主语为whether they will enjoy it，故答案为B)。