Frequency and duraction
I don't know how to ask questions about frequency or about duration in Chinese. How can I ask how often someone does something, or how long something lasts?

For example:
"How often do you look at your phone?" or "How long does this process last?"

Question

Frequency and duraction
I don't know how to ask questions about frequency or about duration in Chinese. How can I ask how often someone does something, or how long something lasts?

For example:
"How often do you look at your phone?" or "How long does this process last?"

Answer

How often do you look at your phone? = 你多久看一次手机？ how often = 多久；

How long does this process last? = 这个过程持续多长时间？how long = 多长（时间），sometimes I translate 'how long' to '多久' as well.

Answer

frequency: 
how often means 多长时间(做)一次（duo chang shi jian (zuo) yi ci), 做means do something.一次 means once. 
The structure in Chinese is: 多长时间＋verb+一次？
How often do you look at your phone?
＝多长时间＋look at 一次＋ phone
=你多长时间看一次手机?

for the duration:
how long does something last= sth 持续多久 （chi xu duo jiu?）or 持续多长时间（chi xu duo chang shi jian）

The structure in Chinese is: Something+ 持续多久/持续多长时间？
How long does this process last? 
= This process+持续多久／持续多长时间？
＝这个过程持续多久？／这个过程持续多长时间？