The sound of the consonant <em>c </em>is a good example of this.
Explanation:
The letter <em>c</em> is not always pronounced the same in Spanish. When it is followed by the vowels <em>a, o </em>or <em>u</em>, the letter <em>c </em>has the same sound as the letter <em>k. </em>
A few words with this hard <em>c </em>sound are:
la cama
el coro
la cucaracha
When it is followed by the vowels <em>e </em>or <em>i, </em>it has the same sound as the <em>s </em>or <em>th</em> in Spain and Equatorial Guinea.
One is positive two is negative three is positive four is negative five is positive six is positive seven is negative eight is negative nine is positive ten is negative. Hope I helped