difficult to pinpoint difficult to place difficult to play difficult to please difficult to practice difficult to predict difficult to predict how difficult to prepare difficult to prevent difficult to process difficult to produce difficult to pronounce difficult to protect difficult to prove difficult to pull difficult to pull off difficult to push difficult to put difficult to put into words difficult to qualify difficult to quantify difficult to quit difficult to raise difficult to reach difficult to read difficult to recall difficult to receive difficult to recognise difficult to recognize difficult to reconcile difficult to recover difficult to recruit difficult to recycle difficult to reduce difficult to refuse difficult to regulate difficult to relax difficult to remain difficult to remember difficult to remove difficult to repair difficult to replace difficult to replicate difficult to reproduce difficult to resist difficult to resolve difficult to restore difficult to retain difficult to return difficult to reverse difficult to run difficult to satisfy difficult to save difficult to say difficult to say exactly difficult to say how difficult to say what difficult to say when difficult to say who difficult to secure difficult to see difficult to select difficult to sell difficult to separate difficult to set difficult to set up difficult to share difficult to shoot difficult to show difficult to sit difficult to sleep difficult to solve difficult to sort difficult to speak difficult to spot difficult to stand difficult to start difficult to stay difficult to steal difficult to stick difficult to stop difficult to store difficult to strike difficult to study difficult to summarize difficult to support difficult to survive difficult to sustain difficult to swallow difficult to switch difficult to take difficult to talk difficult to teach difficult to tell difficult to tell apart difficult to tell the difference difficult to test difficult to think difficult to tolerate