Grammar spot: Prepositions I

Here are a few sentences for you to complete since the prepositions are missing. The prepositions you will have to use are: AT, BY, FOR, IN.
( Answers are below the sentences, so try not to look at them )

1.He sent a copy of his will to his bank....safe keeping.
2. The house is to be sold...auction.
3. You could tell...a glance that he was different.
4.There has been a sharp increase... house prices recently.
5. Did she give you any reason...her behaviour?
6.Multiply six....seven.


ANSWERS:
1.for 2.at 3.at 4.in 5.for 6.by

will = herencia
auction = subasta
sharp = brusco
increase* = aumento

*increase: cuando se trata del sustantivo "aumento" el énfasis o stress se encuentra en la primera sílaba; cuando se trata del verbo "aumentar" debemos poner el énfasis en la última sílaba ( esta regla la siguen la mayoría de los verbos como "decrease", "rebel", ...)