各位前輩好 我想請問以下這句:
Authorities said that the possibility that the incident is linked to the poiso
ning in march of a former Russian spy is a "clear line" of their investigation
.
裡面第一個that應該是名詞子句當said的受詞，但第二個that我就不清楚了，我基礎還不
好感覺一圈又一圈轉不出去，然後還有march後面的of是什麼用法？
非常感謝各位 謝謝