at the age of 与by the time of 与at that time后面分别加什么时态?

at the age of adv.在...岁 She graduated from the high school at the age of 18.by the time是过去完成时的标志,看见这个标志,就一定要用过去完成时.J-Lo Wants to Be Pregnant by the Time of Her 40th Birthday...