vi.

1. 思索；沉思；推測[（+on/upon/about）]
   She speculated about her friend's motives.

   她猜測她朋友的動機。

2. 投機；做投機買賣[（+in）]
   He speculated successfully in mining shares.

   他做礦業股票投機獲得成功。

vt.

1. 推測，推斷[Y][+that]
   He was speculating that this might be his last chance.

   他推測這可能是他的最後一次機會了。

v.

1. form a theory or conjecture without firm evidence.
2. invest in stocks, property, or other ventures in the hope of gain but with the risk of loss.