81.   Questions linger two decades after assassination.

82.   Questions lingered, however, about how they would take shape, and differences between the two sides remained acute.

83.   Questions lingered, however, about how they would take shape, and differences between the two sides remained.

84.   The two leaders still must bridge decades of mistrust over nuclear negotiations, and questions lingered about how their talks would take shape.

85.   U.S. officials have said Russia was using the ban in part to protect its domestic chicken industry, and questions linger about other Russian trade practices regarding chicken.

86.   Yet questions have lingered about its safety.

87.   Questions linger over whether the money might instead be best used to solve problems on Earth.