Identify which two sentences listed below contain weak and hedging expressions:

A、For example, in January this person weighed 60.8 kg for eight days.;
B、It may be necessary for the spider to leave the branch on which it is standing, climb up the stem, and walk out along another branch. ;
C、For example, it is necessary for the spider to leave the branch on which it is standing, climb up the stem, and walk out along another branch. ;
D、There is experimental work to show that a week or ten days may not be long enough and a fortnight to three weeks is probably the best theoretical period.