{\"content\":{\"task\":\"

Can you finish the sentences? Choose the correct option for the missing words.<\\\/p>\",\"blanksList\":[{\"correctAnswerText\":\"get longer\",\"incorrectAnswersList\":[{\"showHighlight\":false,\"highlight\":\"-1\",\"incorrectAnswerText\":\"get shorter\",\"incorrectAnswerFeedback\":\"\"}]},{\"correctAnswerText\":\"redshift\",\"incorrectAnswersList\":[{\"showHighlight\":false,\"highlight\":\"-1\",\"incorrectAnswerText\":\"blueshift\",\"incorrectAnswerFeedback\":\"\"}]},{\"correctAnswerText\":\"blueshifted\",\"incorrectAnswersList\":[{\"showHighlight\":false,\"highlight\":\"1\",\"incorrectAnswerText\":\"redshifted\",\"incorrectAnswerFeedback\":\"\"}]},{\"correctAnswerText\":\"shorter\",\"incorrectAnswersList\":[{\"showHighlight\":false,\"highlight\":\"-1\",\"incorrectAnswerText\":\"longer\",\"incorrectAnswerFeedback\":\"\"}]}],\"blanksText\":\"

If you observe light from a source that moves away from you, the wavelength of the light will _______________. <\\\/p>

This phenomenon is called _____________ .<\\\/p>

If the source of light is approaching us, the light gets _____________ because the wavelength gets ______________.<\\\/p>\"},\"overallFeedback\":[{\"from\":0,\"to\":0,\"feedback\":\"None correct so far.\"},{\"from\":1,\"to\":30,\"feedback\":\"One correct, but you can probably manage more.\"},{\"from\":31,\"to\":99,\"feedback\":\"You have several correct! Can you manage to get all of them?\"},{\"from\":100,\"to\":100,\"feedback\":\"All correct!\"}],\"behaviour\":{\"mode\":\"selection\",\"selectAlternatives\":\"alternatives\",\"selectAlternativeRestriction\":0,\"spellingErrorBehaviour\":\"warn\",\"caseSensitive\":false,\"autoCheck\":false,\"enableSolutionsButton\":false,\"showSolutionsRequiresInput\":true,\"enableRetry\":true,\"enableCheckButton\":true,\"confirmCheckDialog\":false,\"confirmRetryDialog\":false},\"showSolutions\":\"Show solution\",\"tryAgain\":\"Retry\",\"checkAnswer\":\"Check\",\"notFilledOut\":\"Please fill in all blanks to view solution\",\"tipLabel\":\"Tip\",\"spellingMistakeWarning\":\"Check your spelling: @mistake\",\"confirmCheck\":{\"header\":\"Finish?\",\"body\":\"Are you sure you wish to finish?\",\"cancelLabel\":\"Cancel\",\"confirmLabel\":\"Finish\"},\"confirmRetry\":{\"header\":\"Retry?\",\"body\":\"Are you sure you wish to retry?\",\"cancelLabel\":\"Cancel\",\"confirmLabel\":\"Confirm\"},\"scoreBarLabel\":\"You got :num out of :total points\",\"snippets\":[{\"snippetText\":\"

If you talk about how long<\\\/strong> something has been going on until now, you need present perfect progressive<\\\/strong>. (have\\\/has been + ...ing)<\\\/em><\\\/div>\\n\",\"snippetName\":\"present_perf_prog\"}],\"media\":{\"disableImageZooming\":false},\"submitAnswer\":\"Submit\"}