MoreBlanks will improve your English.
MoreBlanks is a simple game to learn English words, it builds on the Blanks application (freely available on the Appstore). It contains over 10.000 words.
About 4 times more than Blanks.
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To get to the option screen press the little i icon on the right side of the main screen over the word definitions.
Select the word you think fits the definition and drag it into the blank on top.