admin sua lai dap an: chung toi hoac chung ta ...
Under tips and notes it says that it can be used as noun or adjective without nominalization yet "chúng tôi cần cạnh tranh" is marked wrong.
Am I missing something?
That reads "We need competitive" instead of "we need competition"
Is sự really necessary here?
To convey the the message properly yes. Without it the sentence becomes "We need to be competitive"