Wie wär's mit einer Mütze? This is an example sentence from my textbook. Does it mean "How about with a cap"? Why is there a " 's " after wär?

How to use "gleich"? what's the meaning of the two sentences? Kommen Sie gleich? Bis gleich.

How to wash clothes in US Hello, guys! I will stay in US for a while. It may seem to be a funny and ridiculous probem for natives, but it is quite a troubling one for us. It is summer and we need to change clothes every day. How often will you use laundry machines? I bought a laundry bag today and I wonder how many clothes you will take to laundry room once a load. In our country, during summer we just wash by hand every day and dry them outside or in the balcony, but it is illegal in US. I've come here recently and where I live only provides public laundry rooms. It is quite inconvenient and troublesome for me.

two sentences with möchten -Was möchtest du gerne? Why using a "gerne" instead of "gern"? -Die möchte ich auch bestellen. Why there is a "Die" before möchte?

How to read [e:] in German? Does the phonetic symbol [e:] in German sound the same with that in English? But why sometimes it sounds like [i:] in English in my textbook audio.