若二项式（x+2）n的展开式的第四项是42，而第三项的二项式系数是14，则x的值

阅读理解

       Li Ping is a Young Pioneer (少先队员). He goes to the wildlife park (野生动物园). When he waits

for a bus at the bus stop, he finds a watch on the road (马路). He asks some people, "Whose watch is it?" But the watch isn't theirs. So he gives it to the policeman.

       Li Ping gets on the bus. There are many people in it. Li Ping sits near the door. An old man gets on

the bus, too. He has no seat (座位).So Li Ping stands up and says: "Here is a seat for you. Grandpa,

please sit here."

根据短文，正确的写T，错误的写F。

( )1. Li Ping finds a watch on the road and gives it to an old man.

( )2. Li Ping goes to the wildlife park by bus.

( )3. There're many people in the bus.

( )4. Li Ping takes the old man's seat.

招潮蟹能准确地按照海水涨落的时间出来活动，这是一种[ ]

A．昼夜节律行为

B．潮汐节律行为

C．季节节律行为

D．迁徙行为

如图所示，比荷为的电子以速度v₀沿AB边射入边长为a的等边三角形匀强磁场区域，为使电子从BC边穿出磁场，磁感应强度B的取值范围为

A．B>

B．B＜

C．B>

D．B＜

某外国投资者拟并购境内某企业并取得实际控制权，下列情形中，应当向商务部进行申报的有( )。

A．涉及重点行业

B．存在影响或可能影响国家经济安全因素

C．安置方案不能满足职工要求

D．导致拥有驰名商标或中华老字号的境内企业实际控制权转移

做好重大危险源辨识和风险评价，定期组织检查，规范登记、整改、销号的全过程管理，完善隐患排查闭环系统。