Which Beatles' song contains the phrase "Guess you know it's true"?

The phrase, "Guess you know it's true" is from the 1964 song "Eight Days a Week" by the Beatles, a very successful rock band. It was written by Paul McCartney and John Lennon, based on an original idea by McCartney. The song was released in the United Kingdom in December 1964 on the fourth studio album "Beatles for Sale". In the United States, it was first issued as a single in February 1965 before appearing on the North American release "Beatles VI", the seventh Capitol Records studio album by the Beatles in the US and Canada.

The song "Eight Days a Week" was the band's seventh No. 1 single on the Billboard Hot 100, having a US chart run that achieved success in just over a year. The single was also No. 1 in Canada, Belgium, and the Netherlands. Unrealistically, the song addresses the prospect of loving somebody forever, for eight days a week. It epitomizes a naivety that one can love beyond scientific limitations (physics - seven days).

The Beatles were an English rock band formed in Liverpool, England in 1960. The group comprised John Lennon, Paul McCartney, George Harrison, and Ringo Starr. This band has been called one of most, if not the most, influential rock band of all time.