Sometimesitisverydifficultto_______someoftheEnglishwords.Eventhenativespeakercannothelp.
Inordertoincreaseouroutput,weneedtoimportmoreproduction_______.
Thisriverissobigthatitisimpossibletobuilda_______underitwithoutmoderntechnology.
Studentswith_______problemsmayapplyforstudentloans.