请教语法题一道

michael_wind

(The astronomy) is the oldest (science), but it (continues) to be (at) the forefront of scientific thought.
答案说是at 错，应该固定用 in the forefront of ,  但是，我认为学科名词不加定冠词，the astronomy 是否应为astronomy,  ?  谢谢

redpassion

特指？
强调？