to straighten /ˈstreɪtn/ /ˈstreɪtn/
to smoothen /smˈuːðən/ /smˈuːðən/
to smooth /smuːð/ /smuːð/
to flatten /ˈflætən/ /ˈflætn/
to clear /klɪr/ /klɪə/
to pay off /peɪ ɔf/ /peɪ ɒf/
to filter /ˈfɪltər/ /ˈfɪltə/
to strain /streɪn/ /streɪn/