Riley Riddles in Reverse, batch 2

Question

_{"post some more sometime :)" -- user @Dragonrage in the comments of Riley Riddles in Reverse}

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Here's another batch of "inverted" Riley riddles. These still work exactly like the ones before:

You get three words. You must find one solution word that you can attach..

• to the beginning of one of the three words, (you have to figure out which one)
• somewhere in the middle of another, and
• to the end of the remaining word,

so that in each case, a new, single word is formed.

All the words here are very random, and some of them are even very rare, but every clue, result, and solution word is going to be strictly valid in Scrabble.

1. sailing - cement - bi
2. rate - onions - scam
3. tan - caste - ka
4. one - regal - stat

If you get stuck, you can write the four solution words together, and the result will be yet another random Scrabble-valid word.

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_{PS. This puzzle format is still very experimental, so please leave feedback and improvement suggestions in the comments. Thanks to those, especially @Riley, who have already done so.}

Answer 1

sailing - cement - bi

ASsailing, cASement, biAS

rate - onions - scam

PIrate, oPInions, scamPI

tan - caste - ka

RATtan, castRATe, kaRAT

one - regal - stat

IONone, regIONal, statION

Leading to:

ASPIRATION