單項(xiàng)選擇題周期函數(shù)隨著其周期逐漸增大,頻率(即譜線間隔()當(dāng)函數(shù)周期變?yōu)闊o(wú)窮大,實(shí)質(zhì)上變?yōu)榉侵芷诤瘮?shù),基頻趨于零

A.愈來(lái)愈小
B、愈來(lái)愈大
C、不變