Help with figuring out commands for test!

Question

These are study guide questions, I would appreciate any help!!
What does the following PowerShell command do?
PS C:> ls | Where-Object { $.PSIsContainer } | ForEach-Object { (ls $ | ? { -not $_.PSIsContainer } | sort LastWriteTime)[0] }
Select one:
Finds all the files that are one subdirectory deep
Searches one subdirectory level deep and finds the least recently modified file in each subdirectory
Recursively searches for the file named "0"
Searches each subdirectory and finds the most recently modified file
Recursively searches for the newest file on the system
What does the following PowerShell command do?
PS C:> Select-String "[0-9]{10}" audit.log
Select one: Searches for the literal string "[0-9]{10}" and returns each line containing the string
Looks for and returns the first instance of the literal string "[0-9]{10}" in the file audit.log
Looks for and returns each line containing 10 consecutive digits in the file audit.log
Looks for and returns the first number that is exactly 10 digits found in the file audit.log
Looks for and returns a 0-9 followed by a 1 or 0 in the file audit.log
What does the following PowerShell command do?
PS C:> ls -r -fo | ? { $_.LastAccessTime -gt (Get-Date).AddDays(-1) } | select LastAccessTime, Name
Select one: Finds all files, excluding hidden files, accessed in the last day and outputs the last access time and filename
Finds all files, excluding hidden files, accessed in the last day and outputs the last access time and the user
Finds all files, including hidden files, accessed in the last day and outputs the last access time and filename
Finds all files, including hidden files, accessed in the last day and outputs the last access time and the user
Finds all files, including hidden files, accessed more than one day ago and outputs the last access time and filename
What does the following PowerShell command do?
PS C:> Get-Process cmd | ? { $_.StartTime -lt (Get-Date).AddHours(-1) } | Stop-Process
Select one: Kills any cmd.exe process that has been running for longer than an hour
Starts cmd.exe and stops it after one hour
Kills any cmd.exe processes that started exactly one hour ago
Kills any cmd.exe process that has started in the past hour
Starts cmd.exe after pausing for one hour
What does the following PowerShell command do?
PS C:> ls \users\ephil\Documents | % { move $.FullName -dest $.FullName.ToLower() }
Select one: Moves each file in \Users\ephil\Documents to a lower directory
Moves each file in \Users\ephil\Documents to the directory named FullNameToLower
Moves files with all lowercase characters to \Users\ephil\Documents
Finds all files containing the words user, ephil or documents and renames them to lower case
Renames each file in \Users\ephil\Documents to lower case

Answer 1

It really doesn't help you learn if we're giving you the answers to questions. That said, there are a number of places where the code you've posted has syntax errors. Any place you see "$" with nothing after it in that code (ie, "$.StartTime" or "ls $ |",
assume they meant to type "$_" ("$_.StartTime", "ls $_ |").
There are also a lot of aliases and partial parameter names in the code.  This may be deliberate, to get you to play around with the commands and figure out what the cryptic notation really means, but I don't think it's very helpful.  We encourage
people to use full command and parameter names in scripts to enhance code clarity; the same standard should be applied to your test questions.  Aliases are an optional convenience if you want to save some typing, once you're comfortable with them.
So, here are the aliases used in your questions, along with their actual command / parameter name:
% : ForEach-Object
? : Where-Object
ls : Get-ChildItem
sort: Sort-Object
select: Select-Object
move: Move-Item
-r:  (as a parameter to ls / Get-ChildItem) -Recurse
-fo: (as a parameter to ls / GetChildItem) -Force
-dest: (as a parameter to move / Move-Item) -Destination
Yes the $_. turned out as $. for some reason.
Could you help me with any of these questions? They will really prepare me well for the test. If you could provide answers for any of them I could then work backwards and figure out how to arrive at the answer.