已知，若点是所在平面内一点，且，当变化时，最大值等于（ ）。

(单选题)Tom often makes his brother ______. (单选题)It is five years since he ______ here. (单选题)My father ______ volleyball with his friends in the gym yest (单选题)—How long have you ______ your bike?—For about two months. (单选题)London is ______ capital of ______ England. (单选题)—What do you do?—______ (单选题)Your brother is ______ to go to school. (单选题)______ a cold winter morning he left ______ Shanghai. (单选题)______ foreigners come to our country every year. (单选题)______ playground is much larger than ______.