The phrase 'explains the reason why' is both correct and usable in written English.
You can use it to explain the cause or rationale of a certain topic. For example: "This passage explains the reason why the economy has been struggling recently."
It also explains the reason why wood has good tactile warmth regardless of seasons against metals, which feel too hot in summer and too cold in winter to touch.
Clare Wenner, head of renewable transport at the UK's Renewable Energy Association, explains: "The reason why it's an issue here in the EU is we've got a very dieselised car park.
And it lucidly explains the reason why pilots of small aeroplanes understand that they are riskier than big ones yet accept the risks, believing that most can be controlled.Flying across America in a private plane is a joy; a journey on a commercial airline can become a nightmare.
That explains the reason why CFD predictions are bigger than FNM results.
This explains the reason why only 7% of tablets are used in the workplace.
This explains the reason why sample using fresh suspension with 1.0 mM CTAB (black line) had the best integrated AR performance.
When she questions his experiments on a monkey, and he explains the reasons why, she replies: "You're right, darling, I'm being silly".
Kinematics and dynamics properties of the vehicle actuated by the tractor are investigated, which explains the reasons why low-power motors and short-range sensors can be used for automated guidance of heavy-duty vehicles.
It explains the reasons why the best workplaces such as Starbucks, Southwest Airlines, Ritz-Carlton and ServiceMaster apply servant leadership.
The fitting parameters of EIS explained the reason why the MSCC exhibited better anticorrosive performance than the MCC.
