Throughout the 20th century, republicans have done which of the following? select all that apply. won majorities in both the house, senate, and presidency during the middle of the century had their strongest showing with ronald reagan who won all but one state mostly lost to democrats in landslide defeats elected dwight d eisenhower- twice lost to jimmy carter and won with incumbent george h. bush

The answers are: 
had their strongest showing with Ronald Reagan who won all but one state
and 
elected Dwight D Eisenhower- twice

Reagan won every state but Wisconsin in 1984, and Eisenhower was elected twice in the 1950s. 
The Republicans virtually never controlled both Houses and the presidency during the mid-20th century. Remember that FDR set the stage for Democrat dominance for years to come. They also didn't mostly lose to Democrats in landslides- a lot of Republican presidents got elected during this time, such as Eisenhower, Nixon, and Reagan. Also, George H W Bush didn't win his incumbent election, he lost to Clinton in 1992.