C. have a sphincter the size of a pinhead .

C.心情郁闷。

One pinhead of the pufferfish poison is sufficient to kill a full grown adult male human .

相当于一针剂量的河豚毒足以使一成年男人丧命。

Spotting the light from a tiny planet across astronomical distances is akin to discerning a red-hot pinhead right next to a floodlight from many kilometres away .

要通过天文距离找出小行星上的光线，就如同去找远在几公里外的那临近照明灯旁边炽热的针头。