Trump made campaign stops in North Carolina, Pennsylvania, Michigan and Wisconsin on Monday, while Biden traveled to Ohio in the day and Pennsylvania on Election Eve.
Trump said last week that he "may" go to Jerusalem for the opening himself.
Trump's tweets sparked a row between the White House and May, who said Trump was "wrong" to re-tweet material from a group she described as spreading "hateful narratives."
Trump has repeatedly suggested Canada was profiting from US trade, and his blistering comments after the G7 meeting drove bilateral relations to their lowest point in decades.
Trump also expressed reservations about Bolton — whom he forced out in September as national security adviser — appearing as a witness because "you don't like people testifying when they didn't leave on good terms". He said his break with Bolton was "due to me, not due to him".
Tu Youyou announced in June that her team has proposed solutions to the problem of artemisinin resistance, providing new evidence that artemisinin is still "the best weapon" against malaria, the world's No. 1 insect-borne infectious disease.
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Trump also said 20 states are planning to reopen their economies.
Trump didn't cite what corruption he believes the Bidens have committed.
Trump's remarks came days after Pyongyang carried out two "important tests" at its Sohae Satellite Launching Ground on Dec 7 and 13.
Trump's recognition of Jerusalem as Israel's capital has been seen as a move seriously diminishing the hope of peace talks between Israel and the Palestinians.