An e-mail address consists _______letters and dots and the symbol‘@’.

—Susan, can you help clean the window?—Why ______? Alice is sitting there doing nothing.

Tony told us ______ funny story, but he forgot ______ ending himself.

— ______ do you usually do at weekends, Susan? — I usually help my parents do some housework.

— The dictionary is a useful                      for understanding new words. — I think so.