应用元素周期律，判断下列语句，其中正确的组合是
①碱金属单质的熔点随原子序数的增大而降低②砹（At）在第VIIA族，其氢化物的稳定大于HC1 ③硒（Se）在第VIA族，SeO2的氧化性强于SO2 ④第二周期非金属元素的气态氢化物溶于水后，水溶液均为酸性⑤铊（Tl）与铝同主族，其单质既能与盐酸反应，又能与氢氧化钠溶液反应⑥第三周期金属元素的最高价氧化物对应水化物，其碱性随原子序数的增大而减弱
| A．①③⑥ | B．①③④ | C．③④⑤ | D．①⑤⑥ |
All the dishes in this menu, ______ otherwise stated, will serve two to three people. 
| A．as | B．if | C．though | D．unless |
The children loved their day trip, and they enjoyed the horse ride ______.
| A．most | B．more | C．less | D．little |
Progress______ so far very good and we are sure that the work will be finished on time.
| A．was | B．had been | C．has been | D．will be |
Charles was alone at home, with_______ looking after him.
| A．someone | B．anyone | C．not one | D．no one |
It is often ______ that human beings are naturally equipped to speak.
| A．said | B．to say | C．saying | D．being said |