 Complete the following phrase:  Three track and field athletes from Botswana participated at the London games after having achieved qualifying standards in their respective events up to a maximum of 3 athletes in each event at the A Standard, and 1 at the B Standard. Track runner Isaac Makwala, competing in the mens 400 metres, did not advance into the semi-finals after finishing fourth in the heats. Amantle Montsho, Botswanas only female athlete and 2011 world champion, was favored to win Botswanas first ever medal in the womens 400 metres, but finished in a disappointing fourth place. Her results became arbitrary, whether her coachs failure to obtain a VISA to the Olympics might have been a contributing factor. 2012 world junior champion and another Olympic hopeful Nijel Amos, however, qualified successfully in the early rounds of the 