sole
「sole」是「僅有、唯一的」,例如:
My sole reason for visiting here was to see Chiang Kai-shek Memorial Hall.(我來這裡的唯一理由,就是參觀中正紀念堂。)
That will be the sole means of access to the building.(那是進入這棟建築物的唯一途徑。)
Claire was the sole survivor of the terrible accident.(克萊兒是這可怕意外事故的唯一倖存者。)
hear a pin drop
「could hear a pin drop」是「鴉雀無聲、 完全安靜,幾乎是『可以聽見針掉落的聲音』」,例如:
As the audience waited for the Nobel Prize winner to speak, you could even hear a pin drop.(聽眾在等待諾貝爾得獎者發表感言時,甚至可以聽到針掉落的聲音。)
After the teacher's outburst, the classroom was so quiet you could hear a pin drop.(老師大發一頓脾氣之後,教室鴉雀無聲。)
It was completely silent before the piano played in front of several thousand people. You could hear a pin drop.(在千人鋼琴彈奏會開始之前,可以說是完全的寂靜。)