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may have had many former owners is on sale mainly in London salerooms has usually been polished before being sold has usually been rejected
by; by takes; by takes; on drives; by
having seated seating seated being seated
having seated to seat seated seating
has her bike takes subway takes train walks
having seated to seat seated seating
takes a rest takes a shower takes her time takes classes
takes over takes after takes out takes in
takes over takes after takes out takes in
take; in takes; in take; on takes; at
having seated seating seated having been seated
He doesn't have Not have Not having He didn't have
take; in takes; in take; on takes; at
takes fetches catches gets
having seated to seat seated Seating
having seated seating seated having been seated
PLA及PLGA降解均属于水解反应 PLA及PLGA降解速度随它们的相对分子质量的增加而减小 PLA在降解初期，其材料的外形和重量有明显变化 PLA及PLGA制备中均可利用羟基铝作催化剂
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