【单选题】The celebration of Thanksgiving Day has been observed to thank ______.
【简答题】What encouraging sign has been observed by experts about Venice?
【单选题】A Pike has, been observed to live, according to Gesner, as long as ______.
A.
any other fresh - water fish
C.
it has the help of the sun's heat
【单选题】The celebration of Thanksgiving Day has been observed to thank ______.