1 low pitch

2 quiet (voice)

3 subdued

4 low-key

5 low-profile

1 fickle

2 multi-variate (math.)

1 to emphasize (a statement)

2 to stress

1 to change

2 to alter

3 to transform

1 air conditioning

2 air conditioner (including units that have a heating mode)

3 classifier: 台 tái

1 nothing much changes (idiom); always the same

2 stuck in a rut

1 to show no understanding of the times (idiom); cannot adapt to current circumstances

2 not amenable to reason

1 unchanging since times immemorial (idiom)

2 unalterable

3 unvarying

4 monotonous

1 customs change with time (idiom); other times, other manners

2 O Tempora, O Mores!

1 constantly changing, ever-varying (idiom)