Problems with Generating Blank-filling Questions from a Text

 Diffit, despite its functionality, does not generate blank-filling questions from a text. 

I looked to Questgen, but it turned out the Blank-filling generation function is a paid function. 

i then turned to Toolsday, which can generate blank-filling questions for free. 

The problem is, the generated blank-filling questions are quite superficial, and do not tap higher-level thinking.