YOU SAID:

I can't think of any on the spot.

INTO JAPANESE

私は、スポット上の任意の考えられない。

BACK INTO ENGLISH

I can not think any over the spot.

INTO JAPANESE

そう考えざるを得ない。

BACK INTO ENGLISH

I can not but think so.

INTO JAPANESE

そう考えざるを得ない。

BACK INTO ENGLISH

I can not but think so.